diff --git a/Telegram/SourceFiles/api/api_updates.cpp b/Telegram/SourceFiles/api/api_updates.cpp
index d3e80896c..7cb1347d5 100644
--- a/Telegram/SourceFiles/api/api_updates.cpp
+++ b/Telegram/SourceFiles/api/api_updates.cpp
@@ -1510,7 +1510,7 @@ void Updates::feedUpdate(const MTPUpdate &update) {
 			return;
 		}
 		auto possiblyReadMentions = base::flat_set<MsgId>();
-		for_const (auto &msgId, d.vmessages().v) {
+		for (const auto &msgId : d.vmessages().v) {
 			if (auto item = session().data().message(channel, msgId.v)) {
 				if (item->isUnreadMedia() || item->isUnreadMention()) {
 					item->markMediaRead();
diff --git a/Telegram/SourceFiles/apiwrap.cpp b/Telegram/SourceFiles/apiwrap.cpp
index ce0cbfcfb..828ca3b6d 100644
--- a/Telegram/SourceFiles/apiwrap.cpp
+++ b/Telegram/SourceFiles/apiwrap.cpp
@@ -500,74 +500,98 @@ void ApiWrap::sendMessageFail(
 	}
 }
 
-void ApiWrap::requestMessageData(ChannelData *channel, MsgId msgId, RequestMessageDataCallback callback) {
-	auto &req = (channel ? _channelMessageDataRequests[channel][msgId] : _messageDataRequests[msgId]);
+void ApiWrap::requestMessageData(
+		ChannelData *channel,
+		MsgId msgId,
+		RequestMessageDataCallback callback) {
+	auto &requests = channel
+		? _channelMessageDataRequests[channel][msgId]
+		: _messageDataRequests[msgId];
 	if (callback) {
-		req.callbacks.append(callback);
+		requests.callbacks.push_back(callback);
+	}
+	if (!requests.requestId) {
+		_messageDataResolveDelayed.call();
 	}
-	if (!req.requestId) _messageDataResolveDelayed.call();
 }
 
-QVector<MTPInputMessage> ApiWrap::collectMessageIds(const MessageDataRequests &requests) {
+QVector<MTPInputMessage> ApiWrap::collectMessageIds(
+		const MessageDataRequests &requests) {
 	auto result = QVector<MTPInputMessage>();
 	result.reserve(requests.size());
-	for (auto i = requests.cbegin(), e = requests.cend(); i != e; ++i) {
-		if (i.value().requestId > 0) continue;
-		result.push_back(MTP_inputMessageID(MTP_int(i.key())));
+	for (const auto &[msgId, request] : requests) {
+		if (request.requestId > 0) {
+			continue;
+		}
+		result.push_back(MTP_inputMessageID(MTP_int(msgId)));
 	}
 	return result;
 }
 
-ApiWrap::MessageDataRequests *ApiWrap::messageDataRequests(ChannelData *channel, bool onlyExisting) {
+auto ApiWrap::messageDataRequests(ChannelData *channel, bool onlyExisting)
+-> MessageDataRequests* {
 	if (channel) {
 		auto i = _channelMessageDataRequests.find(channel);
-		if (i == _channelMessageDataRequests.cend()) {
+		if (i == end(_channelMessageDataRequests)) {
 			if (onlyExisting) {
 				return nullptr;
 			}
-			i = _channelMessageDataRequests.insert(channel, MessageDataRequests());
+			i = _channelMessageDataRequests.emplace(
+				channel,
+				MessageDataRequests()).first;
 		}
-		return &i.value();
+		return &i->second;
 	}
 	return &_messageDataRequests;
 }
 
 void ApiWrap::resolveMessageDatas() {
-	if (_messageDataRequests.isEmpty() && _channelMessageDataRequests.isEmpty()) return;
+	if (_messageDataRequests.empty() && _channelMessageDataRequests.empty()) {
+		return;
+	}
 
-	auto ids = collectMessageIds(_messageDataRequests);
+	const auto ids = collectMessageIds(_messageDataRequests);
 	if (!ids.isEmpty()) {
-		auto requestId = request(MTPmessages_GetMessages(
+		const auto requestId = request(MTPmessages_GetMessages(
 			MTP_vector<MTPInputMessage>(ids)
-		)).done([this](const MTPmessages_Messages &result, mtpRequestId requestId) {
+		)).done([=](
+				const MTPmessages_Messages &result,
+				mtpRequestId requestId) {
 			gotMessageDatas(nullptr, result, requestId);
-		}).fail([this](const MTP::Error &error, mtpRequestId requestId) {
+		}).fail([=](const MTP::Error &error, mtpRequestId requestId) {
 			finalizeMessageDataRequest(nullptr, requestId);
 		}).afterDelay(kSmallDelayMs).send();
-		for (auto &request : _messageDataRequests) {
-			if (request.requestId > 0) continue;
+
+		for (auto &[msgId, request] : _messageDataRequests) {
+			if (request.requestId > 0) {
+				continue;
+			}
 			request.requestId = requestId;
 		}
 	}
 	for (auto j = _channelMessageDataRequests.begin(); j != _channelMessageDataRequests.cend();) {
-		if (j->isEmpty()) {
+		if (j->second.empty()) {
 			j = _channelMessageDataRequests.erase(j);
 			continue;
 		}
-		auto ids = collectMessageIds(j.value());
+		const auto ids = collectMessageIds(j->second);
 		if (!ids.isEmpty()) {
-			auto channel = j.key();
-			auto requestId = request(MTPchannels_GetMessages(
-				j.key()->inputChannel,
+			const auto channel = j->first;
+			const auto requestId = request(MTPchannels_GetMessages(
+				channel->inputChannel,
 				MTP_vector<MTPInputMessage>(ids)
-			)).done([=](const MTPmessages_Messages &result, mtpRequestId requestId) {
+			)).done([=](
+					const MTPmessages_Messages &result,
+					mtpRequestId requestId) {
 				gotMessageDatas(channel, result, requestId);
 			}).fail([=](const MTP::Error &error, mtpRequestId requestId) {
 				finalizeMessageDataRequest(channel, requestId);
 			}).afterDelay(kSmallDelayMs).send();
 
-			for (auto &request : *j) {
-				if (request.requestId > 0) continue;
+			for (auto &[msgId, request] : j->second) {
+				if (request.requestId > 0) {
+					continue;
+				}
 				request.requestId = requestId;
 			}
 		}
@@ -612,16 +636,16 @@ void ApiWrap::finalizeMessageDataRequest(
 	auto requests = messageDataRequests(channel, true);
 	if (requests) {
 		for (auto i = requests->begin(); i != requests->cend();) {
-			if (i.value().requestId == requestId) {
-				for_const (auto &callback, i.value().callbacks) {
-					callback(channel, i.key());
+			if (i->second.requestId == requestId) {
+				for (const auto &callback : i->second.callbacks) {
+					callback(channel, i->first);
 				}
 				i = requests->erase(i);
 			} else {
 				++i;
 			}
 		}
-		if (channel && requests->isEmpty()) {
+		if (channel && requests->empty()) {
 			_channelMessageDataRequests.remove(channel);
 		}
 	}
diff --git a/Telegram/SourceFiles/apiwrap.h b/Telegram/SourceFiles/apiwrap.h
index 9b7257ff2..ba1cdb848 100644
--- a/Telegram/SourceFiles/apiwrap.h
+++ b/Telegram/SourceFiles/apiwrap.h
@@ -416,11 +416,12 @@ public:
 
 private:
 	struct MessageDataRequest {
-		using Callbacks = QList<RequestMessageDataCallback>;
+		using Callbacks = std::vector<RequestMessageDataCallback>;
+
 		mtpRequestId requestId = 0;
 		Callbacks callbacks;
 	};
-	using MessageDataRequests = QMap<MsgId, MessageDataRequest>;
+	using MessageDataRequests = base::flat_map<MsgId, MessageDataRequest>;
 	using SharedMediaType = Storage::SharedMediaType;
 
 	struct StickersByEmoji {
@@ -460,8 +461,11 @@ private:
 		ChannelData *channel,
 		mtpRequestId requestId);
 
-	QVector<MTPInputMessage> collectMessageIds(const MessageDataRequests &requests);
-	MessageDataRequests *messageDataRequests(ChannelData *channel, bool onlyExisting = false);
+	[[nodiscard]] QVector<MTPInputMessage> collectMessageIds(
+		const MessageDataRequests &requests);
+	[[nodiscard]] MessageDataRequests *messageDataRequests(
+		ChannelData *channel,
+		bool onlyExisting = false);
 
 	void gotChatFull(
 		not_null<PeerData*> peer,
@@ -580,7 +584,9 @@ private:
 	base::flat_map<QString, int> _modifyRequests;
 
 	MessageDataRequests _messageDataRequests;
-	QMap<ChannelData*, MessageDataRequests> _channelMessageDataRequests;
+	base::flat_map<
+		ChannelData*,
+		MessageDataRequests> _channelMessageDataRequests;
 	SingleQueuedInvokation _messageDataResolveDelayed;
 
 	using PeerRequests = QMap<PeerData*, mtpRequestId>;
diff --git a/Telegram/SourceFiles/boxes/add_contact_box.cpp b/Telegram/SourceFiles/boxes/add_contact_box.cpp
index eb7ad3ab9..ab5c3c35a 100644
--- a/Telegram/SourceFiles/boxes/add_contact_box.cpp
+++ b/Telegram/SourceFiles/boxes/add_contact_box.cpp
@@ -1452,7 +1452,7 @@ void RevokePublicLinkBox::Inner::mouseReleaseEvent(QMouseEvent *e) {
 void RevokePublicLinkBox::Inner::paintEvent(QPaintEvent *e) {
 	Painter p(this);
 	p.translate(0, _rowsTop);
-	for_const (auto &row, _rows) {
+	for (const auto &row : _rows) {
 		paintChat(p, row, (row.peer == _selected));
 		p.translate(0, _rowHeight);
 	}
diff --git a/Telegram/SourceFiles/boxes/stickers_box.cpp b/Telegram/SourceFiles/boxes/stickers_box.cpp
index 6bfa8ace4..198f41df6 100644
--- a/Telegram/SourceFiles/boxes/stickers_box.cpp
+++ b/Telegram/SourceFiles/boxes/stickers_box.cpp
@@ -470,7 +470,7 @@ void StickersBox::getArchivedDone(
 
 	auto addedSet = false;
 	auto changedSets = false;
-	for_const (const auto &stickerSet, stickers.vsets().v) {
+	for (const auto &stickerSet : stickers.vsets().v) {
 		const MTPDstickerSet *setData = nullptr;
 		switch (stickerSet.type()) {
 		case mtpc_stickerSetCovered: {
@@ -2291,7 +2291,7 @@ int StickersBox::Inner::getRowIndex(uint64 setId) const {
 }
 
 void StickersBox::Inner::setFullOrder(const StickersSetsOrder &order) {
-	for_const (auto setId, order) {
+	for (const auto setId : order) {
 		auto index = getRowIndex(setId);
 		if (index >= 0) {
 			auto row = std::move(_rows[index]);
diff --git a/Telegram/SourceFiles/chat_helpers/field_autocomplete.cpp b/Telegram/SourceFiles/chat_helpers/field_autocomplete.cpp
index 6f0cbfaed..720fe59d9 100644
--- a/Telegram/SourceFiles/chat_helpers/field_autocomplete.cpp
+++ b/Telegram/SourceFiles/chat_helpers/field_autocomplete.cpp
@@ -379,9 +379,12 @@ void FieldAutocomplete::updateFiltered(bool resetScroll) {
 
 		bool listAllSuggestions = _filter.isEmpty();
 		if (_addInlineBots) {
-			for_const (auto user, cRecentInlineBots()) {
-				if (user->isInaccessible()) continue;
-				if (!listAllSuggestions && filterNotPassedByUsername(user)) continue;
+			for (const auto user : cRecentInlineBots()) {
+				if (user->isInaccessible()
+					|| (!listAllSuggestions
+						&& filterNotPassedByUsername(user))) {
+					continue;
+				}
 				mrows.push_back({ user });
 				++recentInlineBots;
 			}
diff --git a/Telegram/SourceFiles/core/utils.h b/Telegram/SourceFiles/core/utils.h
index 2d73b601f..8a9aec63a 100644
--- a/Telegram/SourceFiles/core/utils.h
+++ b/Telegram/SourceFiles/core/utils.h
@@ -32,12 +32,6 @@ inline bool in_range(Value &&value, From &&from, Till &&till) {
 
 } // namespace base
 
-// using for_const instead of plain range-based for loop to ensure usage of const_iterator
-// it is important for the copy-on-write Qt containers
-// if you have "QVector<T*> v" then "for (T * const p : v)" will still call QVector::detach(),
-// while "for_const (T *p, v)" won't and "for_const (T *&p, v)" won't compile
-#define for_const(range_declaration, range_expression) for (range_declaration : std::as_const(range_expression))
-
 static const int32 ScrollMax = INT_MAX;
 
 extern uint64 _SharedMemoryLocation[];
diff --git a/Telegram/SourceFiles/data/data_drafts.h b/Telegram/SourceFiles/data/data_drafts.h
index a8c391d5b..3b7b17a3b 100644
--- a/Telegram/SourceFiles/data/data_drafts.h
+++ b/Telegram/SourceFiles/data/data_drafts.h
@@ -126,7 +126,7 @@ private:
 using HistoryDrafts = base::flat_map<DraftKey, std::unique_ptr<Draft>>;
 
 inline bool draftStringIsEmpty(const QString &text) {
-	for_const (auto ch, text) {
+	for (const auto ch : text) {
 		if (!ch.isSpace()) {
 			return false;
 		}
diff --git a/Telegram/SourceFiles/history/admin_log/history_admin_log_filter.cpp b/Telegram/SourceFiles/history/admin_log/history_admin_log_filter.cpp
index 91b6a8ee1..f13746003 100644
--- a/Telegram/SourceFiles/history/admin_log/history_admin_log_filter.cpp
+++ b/Telegram/SourceFiles/history/admin_log/history_admin_log_filter.cpp
@@ -182,10 +182,12 @@ private:
 	not_null<ChannelData*> _channel;
 
 	QPointer<Ui::Checkbox> _allFlags;
-	QMap<MTPDchannelAdminLogEventsFilter::Flags, QPointer<Ui::Checkbox>> _filterFlags;
+	base::flat_map<
+		MTPDchannelAdminLogEventsFilter::Flags,
+		QPointer<Ui::Checkbox>> _filterFlags;
 
 	QPointer<Ui::Checkbox> _allUsers;
-	QMap<not_null<UserData*>, QPointer<UserCheckbox>> _admins;
+	base::flat_map<not_null<UserData*>, QPointer<UserCheckbox>> _admins;
 	bool _restoringInvariant = false;
 
 	struct Row {
@@ -224,7 +226,7 @@ void FilterBox::Inner::createAllActionsCheckbox(const FilterValue &filter) {
 	) | rpl::start_with_next([=](bool checked) {
 		if (!std::exchange(_restoringInvariant, true)) {
 			auto allChecked = _allFlags->checked();
-			for_const (auto &&checkbox, _filterFlags) {
+			for (const auto &[flag, checkbox] : _filterFlags) {
 				checkbox->setChecked(allChecked);
 			}
 			_restoringInvariant = false;
@@ -241,12 +243,12 @@ void FilterBox::Inner::createActionsCheckboxes(const FilterValue &filter) {
 	auto addFlag = [this, &filter](Flags flag, QString &&text) {
 		auto checked = (filter.flags == 0) || (filter.flags & flag);
 		auto checkbox = addRow(object_ptr<Ui::Checkbox>(this, std::move(text), checked, st::defaultBoxCheckbox), st::adminLogFilterLittleSkip);
-		_filterFlags.insert(flag, checkbox);
+		_filterFlags[flag] = checkbox;
 		checkbox->checkedChanges(
 		) | rpl::start_with_next([=](bool checked) {
 			if (!std::exchange(_restoringInvariant, true)) {
 				auto allChecked = true;
-				for_const (auto &&checkbox, _filterFlags) {
+				for (const auto &[flag, checkbox] : _filterFlags) {
 					if (!checkbox->checked()) {
 						allChecked = false;
 						break;
@@ -285,7 +287,7 @@ void FilterBox::Inner::createAllUsersCheckbox(const FilterValue &filter) {
 	) | rpl::start_with_next([=](bool checked) {
 		if (!std::exchange(_restoringInvariant, true)) {
 			auto allChecked = _allUsers->checked();
-			for_const (auto &&checkbox, _admins) {
+			for (const auto &[user, checkbox] : _admins) {
 				checkbox->setChecked(allChecked);
 			}
 			_restoringInvariant = false;
@@ -297,14 +299,16 @@ void FilterBox::Inner::createAllUsersCheckbox(const FilterValue &filter) {
 }
 
 void FilterBox::Inner::createAdminsCheckboxes(const std::vector<not_null<UserData*>> &admins, const FilterValue &filter) {
-	for (auto user : admins) {
-		auto checked = filter.allUsers || base::contains(filter.admins, user);
-		auto checkbox = addRow(object_ptr<UserCheckbox>(this, user, checked), st::adminLogFilterLittleSkip);
+	for (const auto user : admins) {
+		const auto checked = filter.allUsers || base::contains(filter.admins, user);
+		const auto checkbox = addRow(
+			object_ptr<UserCheckbox>(this, user, checked),
+			st::adminLogFilterLittleSkip);
 		checkbox->checkedChanges(
 		) | rpl::start_with_next([=](bool checked) {
 			if (!std::exchange(_restoringInvariant, true)) {
 				auto allChecked = true;
-				for_const (auto &&checkbox, _admins) {
+				for (const auto &[user, checkbox] : _admins) {
 					if (!checkbox->checked()) {
 						allChecked = false;
 						break;
@@ -319,13 +323,13 @@ void FilterBox::Inner::createAdminsCheckboxes(const std::vector<not_null<UserDat
 				}
 			}
 		}, checkbox->lifetime());
-		_admins.insert(user, checkbox);
+		_admins[user] = checkbox;
 	}
 }
 
 bool FilterBox::Inner::canSave() const {
-	for (auto i = _filterFlags.cbegin(), e = _filterFlags.cend(); i != e; ++i) {
-		if (i.value()->checked()) {
+	for (const auto &[flag, checkbox] : _filterFlags) {
+		if (checkbox->checked()) {
 			return true;
 		}
 	}
@@ -335,9 +339,9 @@ bool FilterBox::Inner::canSave() const {
 FilterValue FilterBox::Inner::filter() const {
 	auto result = FilterValue();
 	auto allChecked = true;
-	for (auto i = _filterFlags.cbegin(), e = _filterFlags.cend(); i != e; ++i) {
-		if (i.value()->checked()) {
-			result.flags |= i.key();
+	for (const auto &[flag, checkbox] : _filterFlags) {
+		if (checkbox->checked()) {
+			result.flags |= flag;
 		} else {
 			allChecked = false;
 		}
@@ -348,9 +352,9 @@ FilterValue FilterBox::Inner::filter() const {
 	result.allUsers = _allUsers->checked();
 	if (!result.allUsers) {
 		result.admins.reserve(_admins.size());
-		for (auto i = _admins.cbegin(), e = _admins.cend(); i != e; ++i) {
-			if (i.value()->checked()) {
-				result.admins.push_back(i.key());
+		for (const auto &[user, checkbox] : _admins) {
+			if (checkbox->checked()) {
+				result.admins.push_back(user);
 			}
 		}
 	}
diff --git a/Telegram/SourceFiles/history/history_item_components.cpp b/Telegram/SourceFiles/history/history_item_components.cpp
index 1a7b19496..4eebda25e 100644
--- a/Telegram/SourceFiles/history/history_item_components.cpp
+++ b/Telegram/SourceFiles/history/history_item_components.cpp
@@ -549,7 +549,7 @@ void ReplyKeyboard::resize(int width, int height) {
 		int widthForText = widthForButtons;
 		int widthOfText = 0;
 		int maxMinButtonWidth = 0;
-		for_const (auto &button, row) {
+		for (const auto &button : row) {
 			widthOfText += qMax(button.text.maxWidth(), 1);
 			int minButtonWidth = _st->minButtonWidth(button.type);
 			widthForText -= minButtonWidth;
@@ -559,7 +559,7 @@ void ReplyKeyboard::resize(int width, int height) {
 		bool enough = (widthForButtons - s * maxMinButtonWidth) >= widthOfText;
 
 		float64 x = 0;
-		for (Button &button : row) {
+		for (auto &button : row) {
 			int buttonw = qMax(button.text.maxWidth(), 1);
 			float64 textw = buttonw, minw = _st->minButtonWidth(button.type);
 			float64 w = textw;
@@ -587,10 +587,10 @@ void ReplyKeyboard::resize(int width, int height) {
 }
 
 bool ReplyKeyboard::isEnoughSpace(int width, const style::BotKeyboardButton &st) const {
-	for_const (auto &row, _rows) {
+	for (const auto &row : _rows) {
 		int s = row.size();
 		int widthLeft = width - ((s - 1) * st.margin + s * 2 * st.padding);
-		for_const (auto &button, row) {
+		for (const auto &button : row) {
 			widthLeft -= qMax(button.text.maxWidth(), 1);
 			if (widthLeft < 0) {
 				if (row.size() > 3) {
@@ -662,8 +662,8 @@ void ReplyKeyboard::paint(
 ClickHandlerPtr ReplyKeyboard::getLink(QPoint point) const {
 	Assert(_width > 0);
 
-	for_const (auto &row, _rows) {
-		for_const (auto &button, row) {
+	for (const auto &row : _rows) {
+		for (const auto &button : row) {
 			QRect rect(button.rect);
 
 			// just ignore the buttons that didn't layout well
diff --git a/Telegram/SourceFiles/history/history_service.cpp b/Telegram/SourceFiles/history/history_service.cpp
index f74aa0b24..b7e911ed9 100644
--- a/Telegram/SourceFiles/history/history_service.cpp
+++ b/Telegram/SourceFiles/history/history_service.cpp
@@ -951,7 +951,7 @@ void HistoryService::setServiceText(const PreparedText &prepared) {
 		prepared.text,
 		Ui::ItemTextServiceOptions());
 	auto linkIndex = 0;
-	for_const (auto &link, prepared.links) {
+	for (const auto &link : prepared.links) {
 		// Link indices start with 1.
 		_text.setLink(++linkIndex, link);
 	}
diff --git a/Telegram/SourceFiles/profile/profile_block_group_members.cpp b/Telegram/SourceFiles/profile/profile_block_group_members.cpp
index 4b38c9514..90257866d 100644
--- a/Telegram/SourceFiles/profile/profile_block_group_members.cpp
+++ b/Telegram/SourceFiles/profile/profile_block_group_members.cpp
@@ -233,7 +233,7 @@ void GroupMembersWidget::sortMembers() {
 void GroupMembersWidget::updateOnlineCount() {
 	bool onlyMe = true;
 	int newOnlineCount = 0;
-	for_const (auto item, items()) {
+	for (const auto item : items()) {
 		auto member = getMember(item);
 		auto user = member->user();
 		auto isOnline = !user->isBot() && Data::OnlineTextActive(member->onlineTill, _now);
@@ -433,7 +433,7 @@ void GroupMembersWidget::updateOnlineDisplay() {
 		_now = base::unixtime::now();
 
 		bool changed = false;
-		for_const (auto item, items()) {
+		for (const auto item : items()) {
 			if (!item->statusHasOnlineColor) {
 				if (!item->peer->isSelf()) {
 					continue;
diff --git a/Telegram/SourceFiles/profile/profile_block_peer_list.cpp b/Telegram/SourceFiles/profile/profile_block_peer_list.cpp
index 7ab81b1bc..4f5918398 100644
--- a/Telegram/SourceFiles/profile/profile_block_peer_list.cpp
+++ b/Telegram/SourceFiles/profile/profile_block_peer_list.cpp
@@ -63,8 +63,9 @@ void PeerListWidget::paintContents(Painter &p) {
 	auto left = getListLeft();
 	auto top = getListTop();
 
-	auto from = floorclamp(_visibleTop - top, _st.height, 0, _items.size());
-	auto to = ceilclamp(_visibleBottom - top, _st.height, 0, _items.size());
+	const auto count = int(_items.size());
+	auto from = floorclamp(_visibleTop - top, _st.height, 0, count);
+	auto to = ceilclamp(_visibleBottom - top, _st.height, 0, count);
 	for (auto i = from; i < to; ++i) {
 		auto y = top + i * _st.height;
 		auto selected = (_pressed >= 0) ? (i == _pressed) : (i == _selected);
@@ -147,7 +148,7 @@ void PeerListWidget::mousePressEvent(QMouseEvent *e) {
 	_pressed = _selected;
 	_pressedRemove = _selectedRemove;
 	if (_pressed >= 0 && !_pressedRemove) {
-		auto item = _items[_pressed];
+		const auto item = _items[_pressed];
 		if (!item->ripple) {
 			auto memberRowWidth = rowWidth();
 			auto mask = Ui::RippleAnimation::rectMask(QSize(memberRowWidth, _st.height));
@@ -170,7 +171,7 @@ void PeerListWidget::mousePressReleased(Qt::MouseButton button) {
 	auto pressed = std::exchange(_pressed, -1);
 	auto pressedRemove = base::take(_pressedRemove);
 	if (pressed >= 0 && pressed < _items.size()) {
-		if (auto &ripple = _items[pressed]->ripple) {
+		if (const auto &ripple = _items[pressed]->ripple) {
 			ripple->lastStop();
 		}
 		if (pressed == _selected && pressedRemove == _selectedRemove && button == Qt::LeftButton) {
@@ -274,7 +275,7 @@ void PeerListWidget::preloadPhotos() {
 }
 
 void PeerListWidget::refreshVisibility() {
-	setVisible(!_items.isEmpty());
+	setVisible(!_items.empty());
 }
 
 } // namespace Profile
diff --git a/Telegram/SourceFiles/profile/profile_block_peer_list.h b/Telegram/SourceFiles/profile/profile_block_peer_list.h
index 69231da3b..002db0233 100644
--- a/Telegram/SourceFiles/profile/profile_block_peer_list.h
+++ b/Telegram/SourceFiles/profile/profile_block_peer_list.h
@@ -52,7 +52,7 @@ public:
 
 	int getListLeft() const;
 
-	const QList<Item*> &items() const {
+	const std::vector<Item*> &items() const {
 		return _items;
 	}
 	int itemsCount() const {
@@ -129,7 +129,7 @@ private:
 	Fn<void(PeerData*)> _removedCallback;
 	Fn<void(Item*)> _updateItemCallback;
 
-	QList<Item*> _items;
+	std::vector<Item*> _items;
 
 	int _visibleTop = 0;
 	int _visibleBottom = 0;
diff --git a/Telegram/SourceFiles/settings/settings_notifications.cpp b/Telegram/SourceFiles/settings/settings_notifications.cpp
index 1cdc3f095..17c00d445 100644
--- a/Telegram/SourceFiles/settings/settings_notifications.cpp
+++ b/Telegram/SourceFiles/settings/settings_notifications.cpp
@@ -98,7 +98,7 @@ private:
 
 	int _oldCount;
 
-	QVector<SampleWidget*> _cornerSamples[4];
+	std::vector<SampleWidget*> _cornerSamples[4];
 
 };
 
@@ -350,7 +350,8 @@ void NotificationsCount::setOverCorner(ScreenCorner corner) {
 		if (corner == _overCorner) {
 			return;
 		}
-		for_const (auto widget, _cornerSamples[static_cast<int>(_overCorner)]) {
+		const auto index = static_cast<int>(_overCorner);
+		for (const auto widget : _cornerSamples[index]) {
 			widget->hideFast();
 		}
 	} else {
@@ -362,7 +363,7 @@ void NotificationsCount::setOverCorner(ScreenCorner corner) {
 	_overCorner = corner;
 
 	auto &samples = _cornerSamples[static_cast<int>(_overCorner)];
-	auto samplesAlready = samples.size();
+	auto samplesAlready = int(samples.size());
 	auto samplesNeeded = _oldCount;
 	auto samplesLeave = qMin(samplesAlready, samplesNeeded);
 	for (int i = 0; i != samplesLeave; ++i) {
@@ -394,8 +395,8 @@ void NotificationsCount::clearOverCorner() {
 		Core::App().notifications().notifySettingsChanged(
 			ChangeType::DemoIsHidden);
 
-		for_const (const auto &samples, _cornerSamples) {
-			for_const (const auto widget, samples) {
+		for (const auto &samples : _cornerSamples) {
+			for (const auto widget : samples) {
 				widget->hideFast();
 			}
 		}
@@ -426,8 +427,8 @@ void NotificationsCount::mouseReleaseEvent(QMouseEvent *e) {
 }
 
 NotificationsCount::~NotificationsCount() {
-	for_const (auto &samples, _cornerSamples) {
-		for_const (auto widget, samples) {
+	for (const auto &samples : _cornerSamples) {
+		for (const auto widget : samples) {
 			widget->detach();
 		}
 	}
diff --git a/Telegram/SourceFiles/storage/storage_account.cpp b/Telegram/SourceFiles/storage/storage_account.cpp
index 659321e19..8d1e5010a 100644
--- a/Telegram/SourceFiles/storage/storage_account.cpp
+++ b/Telegram/SourceFiles/storage/storage_account.cpp
@@ -2258,7 +2258,7 @@ void Account::readInstalledMasks() {
 }
 
 void Account::writeSavedGifs() {
-	auto &saved = _owner->session().data().stickers().savedGifs();
+	const auto &saved = _owner->session().data().stickers().savedGifs();
 	if (saved.isEmpty()) {
 		if (_savedGifsKey) {
 			ClearKey(_savedGifsKey, _basePath);
@@ -2267,7 +2267,7 @@ void Account::writeSavedGifs() {
 		}
 	} else {
 		quint32 size = sizeof(quint32); // count
-		for_const (auto gif, saved) {
+		for (const auto gif : saved) {
 			size += Serialize::Document::sizeInStream(gif);
 		}
 
@@ -2277,7 +2277,7 @@ void Account::writeSavedGifs() {
 		}
 		EncryptedDescriptor data(size);
 		data.stream << quint32(saved.size());
-		for_const (auto gif, saved) {
+		for (const auto gif : saved) {
 			Serialize::Document::writeToStream(data.stream, gif);
 		}
 		FileWriteDescriptor file(_savedGifsKey, _basePath);
diff --git a/Telegram/SourceFiles/ui/widgets/multi_select.cpp b/Telegram/SourceFiles/ui/widgets/multi_select.cpp
index cd95b9e20..fc4d0dd77 100644
--- a/Telegram/SourceFiles/ui/widgets/multi_select.cpp
+++ b/Telegram/SourceFiles/ui/widgets/multi_select.cpp
@@ -188,7 +188,7 @@ QRect MultiSelect::Item::paintArea(int outerWidth) const {
 		return rect();
 	}
 	auto yMin = 0, yMax = 0;
-	for_const (auto &copy, _copies) {
+	for (const auto &copy : _copies) {
 		accumulate_max(yMax, copy.y);
 		if (yMin) {
 			accumulate_min(yMin, copy.y);
@@ -671,7 +671,7 @@ void MultiSelect::Inner::computeItemsGeometry(int newWidth) {
 	auto itemTop = 0;
 	auto widthLeft = newWidth;
 	auto maxVisiblePadding = qMax(_st.padding.left(), _st.padding.right());
-	for_const (auto &item, _items) {
+	for (const auto &item : _items) {
 		auto itemWidth = item->getWidth();
 		Assert(itemWidth <= newWidth);
 		if (itemWidth > widthLeft) {
@@ -721,7 +721,7 @@ void MultiSelect::Inner::finishHeightAnimation() {
 }
 
 void MultiSelect::Inner::setItemText(uint64 itemId, const QString &text) {
-	for_const (auto &item, _items) {
+	for (const auto &item : _items) {
 		if (item->id() == itemId) {
 			item->setText(text);
 			updateItemsGeometry();
@@ -783,7 +783,7 @@ int MultiSelect::Inner::getItemsCount() const {
 QVector<uint64> MultiSelect::Inner::getItems() const {
 	auto result = QVector<uint64>();
 	result.reserve(_items.size());
-	for_const (auto &item, _items) {
+	for (const auto &item : _items) {
 		result.push_back(item->id());
 	}
 	return result;
diff --git a/Telegram/SourceFiles/window/notifications_manager_default.cpp b/Telegram/SourceFiles/window/notifications_manager_default.cpp
index 02bd82d75..9a058d3a7 100644
--- a/Telegram/SourceFiles/window/notifications_manager_default.cpp
+++ b/Telegram/SourceFiles/window/notifications_manager_default.cpp
@@ -98,7 +98,7 @@ QPixmap Manager::hiddenUserpicPlaceholder() const {
 }
 
 bool Manager::hasReplyingNotification() const {
-	for_const (auto &notification, _notifications) {
+	for (const auto &notification : _notifications) {
 		if (notification->isReplying()) {
 			return true;
 		}
@@ -110,7 +110,7 @@ void Manager::settingsChanged(ChangeType change) {
 	if (change == ChangeType::Corner) {
 		auto startPosition = notificationStartPosition();
 		auto shiftDirection = notificationShiftDirection();
-		for_const (auto &notification, _notifications) {
+		for (const auto &notification : _notifications) {
 			notification->updatePosition(startPosition, shiftDirection);
 		}
 		if (_hideAll) {
@@ -142,7 +142,7 @@ void Manager::settingsChanged(ChangeType change) {
 }
 
 void Manager::demoMasterOpacityCallback() {
-	for_const (auto &notification, _notifications) {
+	for (const auto &notification : _notifications) {
 		notification->updateOpacity();
 	}
 	if (_hideAll) {
@@ -173,7 +173,7 @@ void Manager::checkLastInput() {
 void Manager::startAllHiding() {
 	if (!hasReplyingNotification()) {
 		int notHidingCount = 0;
-		for_const (auto &notification, _notifications) {
+		for (const auto &notification : _notifications) {
 			if (notification->isShowing()) {
 				++notHidingCount;
 			} else {
@@ -188,7 +188,7 @@ void Manager::startAllHiding() {
 }
 
 void Manager::stopAllHiding() {
-	for_const (auto &notification, _notifications) {
+	for (const auto &notification : _notifications) {
 		notification->stopHiding();
 	}
 	if (_hideAll) {
@@ -400,7 +400,7 @@ void Manager::doClearFromItem(not_null<HistoryItem*> item) {
 	}), _queuedNotifications.cend());
 
 	auto showNext = false;
-	for_const (auto &notification, _notifications) {
+	for (const auto &notification : _notifications) {
 		if (notification->unlinkItem(item)) {
 			showNext = true;
 		}
@@ -424,7 +424,7 @@ bool Manager::doSkipFlashBounce() const {
 }
 
 void Manager::doUpdateAll() {
-	for_const (auto &notification, _notifications) {
+	for (const auto &notification : _notifications) {
 		notification->updateNotifyDisplay();
 	}
 }
diff --git a/Telegram/SourceFiles/window/themes/window_theme_editor_block.cpp b/Telegram/SourceFiles/window/themes/window_theme_editor_block.cpp
index 9212e21e6..ec23105fe 100644
--- a/Telegram/SourceFiles/window/themes/window_theme_editor_block.cpp
+++ b/Telegram/SourceFiles/window/themes/window_theme_editor_block.cpp
@@ -55,11 +55,11 @@ public:
 		fillSearchIndex();
 	}
 
-	const OrderedSet<QString> &searchWords() const {
+	const base::flat_set<QString> &searchWords() const {
 		return _searchWords;
 	}
 	bool searchWordsContain(const QString &needle) const {
-		for_const (auto &word, _searchWords) {
+		for (const auto &word : _searchWords) {
 			if (word.startsWith(needle)) {
 				return true;
 			}
@@ -67,7 +67,7 @@ public:
 		return false;
 	}
 
-	const OrderedSet<QChar> &searchStartChars() const {
+	const base::flat_set<QChar> &searchStartChars() const {
 		return _searchStartChars;
 	}
 
@@ -106,8 +106,8 @@ private:
 	QString _valueString;
 	Ui::Text::String _description = { st::windowMinWidth / 2 };
 
-	OrderedSet<QString> _searchWords;
-	OrderedSet<QChar> _searchStartChars;
+	base::flat_set<QString> _searchWords;
+	base::flat_set<QChar> _searchStartChars;
 
 	int _top = 0;
 	int _height = 0;
@@ -154,11 +154,16 @@ void EditorBlock::Row::fillValueString() {
 void EditorBlock::Row::fillSearchIndex() {
 	_searchWords.clear();
 	_searchStartChars.clear();
-	auto toIndex = _name + ' ' + _copyOf + ' ' + TextUtilities::RemoveAccents(_description.toString()) + ' ' + _valueString;
-	auto words = toIndex.toLower().split(SearchSplitter, base::QStringSkipEmptyParts);
-	for_const (auto &word, words) {
-		_searchWords.insert(word);
-		_searchStartChars.insert(word[0]);
+	const auto toIndex = _name
+		+ ' ' + _copyOf
+		+ ' ' + TextUtilities::RemoveAccents(_description.toString())
+		+ ' ' + _valueString;
+	const auto words = toIndex.toLower().split(
+		SearchSplitter,
+		base::QStringSkipEmptyParts);
+	for (const auto &word : words) {
+		_searchWords.emplace(word);
+		_searchStartChars.emplace(word[0]);
 	}
 }
 
@@ -252,7 +257,7 @@ void EditorBlock::addToSearch(const Row &row) {
 	if (!query.isEmpty()) resetSearch();
 
 	auto index = findRowIndex(&row);
-	for_const (auto ch, row.searchStartChars()) {
+	for (const auto ch : row.searchStartChars()) {
 		_searchIndex[ch].insert(index);
 	}
 
@@ -264,12 +269,12 @@ void EditorBlock::removeFromSearch(const Row &row) {
 	if (!query.isEmpty()) resetSearch();
 
 	auto index = findRowIndex(&row);
-	for_const (auto ch, row.searchStartChars()) {
-		auto it = _searchIndex.find(ch);
-		if (it != _searchIndex.cend()) {
-			it->remove(index);
-			if (it->isEmpty()) {
-				_searchIndex.erase(it);
+	for (const auto ch : row.searchStartChars()) {
+		const auto i = _searchIndex.find(ch);
+		if (i != end(_searchIndex)) {
+			i->second.remove(index);
+			if (i->second.empty()) {
+				_searchIndex.erase(i);
 			}
 		}
 	}
@@ -339,7 +344,9 @@ void EditorBlock::scrollToSelected() {
 }
 
 void EditorBlock::searchByQuery(QString query) {
-	auto words = TextUtilities::PrepareSearchWords(query, &SearchSplitter);
+	const auto words = TextUtilities::PrepareSearchWords(
+		query,
+		&SearchSplitter);
 	query = words.isEmpty() ? QString() : words.join(' ');
 	if (_searchQuery != query) {
 		setSelected(-1);
@@ -348,28 +355,28 @@ void EditorBlock::searchByQuery(QString query) {
 		_searchQuery = query;
 		_searchResults.clear();
 
-		auto toFilter = OrderedSet<int>();
-		for_const (auto &word, words) {
+		auto toFilter = (base::flat_set<int>*)nullptr;
+		for (const auto &word : words) {
 			if (word.isEmpty()) continue;
 
-			auto testToFilter = _searchIndex.value(word[0]);
-			if (testToFilter.isEmpty()) {
-				toFilter.clear();
+			const auto i = _searchIndex.find(word[0]);
+			if (i == end(_searchIndex) || i->second.empty()) {
+				toFilter = nullptr;
 				break;
-			} else if (toFilter.isEmpty() || testToFilter.size() < toFilter.size()) {
-				toFilter = testToFilter;
+			} else if (!toFilter || i->second.size() < toFilter->size()) {
+				toFilter = &i->second;
 			}
 		}
-		if (!toFilter.isEmpty()) {
-			auto allWordsFound = [&words](const Row &row) {
-				for_const (auto &word, words) {
+		if (toFilter) {
+			const auto allWordsFound = [&](const Row &row) {
+				for (const auto &word : words) {
 					if (!row.searchWordsContain(word)) {
 						return false;
 					}
 				}
 				return true;
 			};
-			for_const (auto index, toFilter) {
+			for (const auto index : *toFilter) {
 				if (allWordsFound(_data[index])) {
 					_searchResults.push_back(index);
 				}
@@ -423,7 +430,7 @@ void EditorBlock::sortByDistance(const QColor &to) {
 template <typename Callback>
 void EditorBlock::enumerateRows(Callback callback) {
 	if (isSearch()) {
-		for_const (auto index, _searchResults) {
+		for (const auto index : _searchResults) {
 			if (!callback(_data[index])) {
 				break;
 			}
@@ -440,7 +447,7 @@ void EditorBlock::enumerateRows(Callback callback) {
 template <typename Callback>
 void EditorBlock::enumerateRows(Callback callback) const {
 	if (isSearch()) {
-		for_const (auto index, _searchResults) {
+		for (const auto index : _searchResults) {
 			if (!callback(_data[index])) {
 				break;
 			}
diff --git a/Telegram/SourceFiles/window/themes/window_theme_editor_block.h b/Telegram/SourceFiles/window/themes/window_theme_editor_block.h
index 05d93593e..8352e41b0 100644
--- a/Telegram/SourceFiles/window/themes/window_theme_editor_block.h
+++ b/Telegram/SourceFiles/window/themes/window_theme_editor_block.h
@@ -144,8 +144,8 @@ private:
 	QMap<QString, int> _indices;
 
 	QString _searchQuery;
-	QVector<int> _searchResults;
-	QMap<QChar, OrderedSet<int>> _searchIndex;
+	std::vector<int> _searchResults;
+	base::flat_map<QChar, base::flat_set<int>> _searchIndex;
 
 	int _selected = -1;
 	int _pressed = -1;