diff --git a/Telegram/SourceFiles/storage/file_upload.cpp b/Telegram/SourceFiles/storage/file_upload.cpp
index b718ed95b..3028b3e6d 100644
--- a/Telegram/SourceFiles/storage/file_upload.cpp
+++ b/Telegram/SourceFiles/storage/file_upload.cpp
@@ -52,6 +52,13 @@ constexpr auto kUploadRequestInterval = crl::time(200);
 // How much time without upload causes additional session kill.
 constexpr auto kKillSessionTimeout = 15 * crl::time(1000);
 
+// How much wait after session kill before killing another one.
+constexpr auto kWaitForNormalizeTimeout = 8 * crl::time(1000);
+
+constexpr auto kMaxSessionsCount = 8;
+constexpr auto kFastRequestThreshold = 1 * crl::time(1000);
+constexpr auto kSlowRequestThreshold = 8 * crl::time(1000);
+
 [[nodiscard]] const char *ThumbnailFormat(const QString &mime) {
 	return Core::IsMimeSticker(mime) ? "WEBP" : "JPG";
 }
@@ -70,9 +77,9 @@ struct Uploader::Entry {
 	not_null<std::vector<QByteArray>*> parts;
 	uint64 partsOfId = 0;
 
-	int partsSent = 0;
-	int partsWaiting = 0;
-	int64 partsSentSize = 0;
+	int64 sentSize = 0;
+	ushort partsSent = 0;
+	ushort partsWaiting = 0;
 
 	HashMd5 md5Hash;
 
@@ -80,9 +87,9 @@ struct Uploader::Entry {
 	int64 docSize = 0;
 	int64 docSentSize = 0;
 	int docPartSize = 0;
-	int docPartsSent = 0;
-	int docPartsCount = 0;
-	int docPartsWaiting = 0;
+	ushort docPartsSent = 0;
+	ushort docPartsCount = 0;
+	ushort docPartsWaiting = 0;
 
 };
 
@@ -90,8 +97,10 @@ struct Uploader::Request {
 	FullMsgId itemId;
 	crl::time sent = 0;
 	QByteArray bytes;
-	int dcIndex = 0;
+	ushort part = 0;
+	uchar dcIndex = 0;
 	bool docPart = false;
+	bool bigPart = false;
 	bool nonPremiumDelayed = false;
 };
 
@@ -138,7 +147,7 @@ bool Uploader::Entry::setPartSize(int partSize) {
 
 Uploader::Uploader(not_null<ApiWrap*> api)
 : _api(api)
-, _nextTimer([=] { maybeSendNext(); })
+, _nextTimer([=] { maybeSend(); })
 , _stopSessionsTimer([=] { stopSessions(); }) {
 	const auto session = &_api->session();
 	photoReady(
@@ -317,7 +326,9 @@ void Uploader::upload(
 		}
 	}
 	_queue.push_back({ itemId, file });
-	maybeSendNext();
+	if (!_nextTimer.isActive()) {
+		maybeSend();
+	}
 }
 
 void Uploader::failed(FullMsgId itemId) {
@@ -330,7 +341,7 @@ void Uploader::failed(FullMsgId itemId) {
 	cancelRequests(itemId);
 	maybeFinishFront();
 	crl::on_main(this, [=] {
-		maybeSendNext();
+		maybeSend();
 	});
 }
 
@@ -361,6 +372,7 @@ void Uploader::stopSessions() {
 			_api->instance().stopSession(MTP::uploadDcId(i));
 		}
 		_sentPerDcIndex.clear();
+		_dcIndicesWithFastRequests.clear();
 	}
 }
 
@@ -394,7 +406,181 @@ QByteArray Uploader::readDocPart(not_null<Entry*> entry) {
 	return checked(entry->docFile->read(entry->docPartSize));
 }
 
-void Uploader::maybeSendNext() {
+bool Uploader::canAddDcIndex() const {
+	const auto count = int(_sentPerDcIndex.size());
+	return (count < kMaxSessionsCount)
+		&& (count == int(_dcIndicesWithFastRequests.size()));
+}
+
+std::optional<uchar> Uploader::chooseDcIndexForNextRequest(
+		const base::flat_set<uchar> &used) {
+	for (auto i = 0, count = int(_sentPerDcIndex.size()); i != count; ++i) {
+		if (!_sentPerDcIndex[i] && !used.contains(i)) {
+			return i;
+		}
+	}
+	if (canAddDcIndex()) {
+		const auto result = int(_sentPerDcIndex.size());
+		_sentPerDcIndex.push_back(0);
+		_dcIndicesWithFastRequests.clear();
+		_latestDcIndexAdded = crl::now();
+
+		DEBUG_LOG(("Uploader: Added dc index %1.").arg(result));
+		return result;
+	}
+	auto result = std::optional<int>();
+	for (auto i = 0, count = int(_sentPerDcIndex.size()); i != count; ++i) {
+		if (!used.contains(i)
+			&& (!result.has_value()
+				|| _sentPerDcIndex[i] < _sentPerDcIndex[*result])) {
+			result = i;
+		}
+	}
+	return result;
+}
+
+Uploader::Entry *Uploader::chooseEntryForNextRequest() {
+	if (!_pendingFromRemovedDcIndices.empty()) {
+		const auto itemId = _pendingFromRemovedDcIndices.front().itemId;
+		const auto i = ranges::find(_queue, itemId, &Entry::itemId);
+		Assert(i != end(_queue));
+		return &*i;
+	}
+
+	for (auto i = begin(_queue); i != end(_queue); ++i) {
+		if (i->partsSent < i->parts->size()
+			|| i->docPartsSent < i->docPartsCount) {
+			return &*i;
+		}
+	}
+	return nullptr;
+}
+
+auto Uploader::sendPart(not_null<Entry*> entry, uchar dcIndex)
+-> SendResult {
+	return !_pendingFromRemovedDcIndices.empty()
+		? sendPendingPart(entry, dcIndex)
+		: (entry->partsSent < entry->parts->size())
+		? sendSlicedPart(entry, dcIndex)
+		: sendDocPart(entry, dcIndex);
+}
+
+template <typename Prepared>
+void Uploader::sendPreparedRequest(Prepared &&prepared, Request &&request) {
+	_sentPerDcIndex[request.dcIndex] += int(request.bytes.size());
+
+	const auto requestId = _api->request(
+		std::move(prepared)
+	).done([=](const MTPBool &result, mtpRequestId requestId) {
+		partLoaded(result, requestId);
+	}).fail([=](const MTP::Error &error, mtpRequestId requestId) {
+		partFailed(error, requestId);
+	}).toDC(MTP::uploadDcId(request.dcIndex)).send();
+
+	request.sent = crl::now();
+	_requests.emplace(requestId, std::move(request));
+}
+
+auto Uploader::sendPendingPart(not_null<Entry*> entry, uchar dcIndex)
+-> SendResult {
+	Expects(!_pendingFromRemovedDcIndices.empty());
+	Expects(_pendingFromRemovedDcIndices.front().itemId == entry->itemId);
+
+	auto request = std::move(_pendingFromRemovedDcIndices.front());
+	_pendingFromRemovedDcIndices.erase(begin(_pendingFromRemovedDcIndices));
+
+	const auto part = request.part;
+	const auto bytes = request.bytes;
+	request.dcIndex = dcIndex;
+	if (request.bigPart) {
+		sendPreparedRequest(MTPupload_SaveBigFilePart(
+			MTP_long(entry->file->id),
+			MTP_int(part),
+			MTP_int(entry->docPartsCount),
+			MTP_bytes(bytes)
+		), std::move(request));
+	} else {
+		const auto id = request.docPart ? entry->file->id : entry->partsOfId;
+		sendPreparedRequest(MTPupload_SaveFilePart(
+			MTP_long(id),
+			MTP_int(part),
+			MTP_bytes(bytes)
+		), std::move(request));
+	}
+	return SendResult::Success;
+}
+
+auto Uploader::sendDocPart(not_null<Entry*> entry, uchar dcIndex)
+-> SendResult {
+	const auto itemId = entry->itemId;
+	const auto alreadySent = _sentPerDcIndex[dcIndex];
+	const auto willProbablyBeSent = entry->docPartSize;
+	if (alreadySent + willProbablyBeSent >= kMaxUploadPerSession) {
+		return SendResult::DcIndexFull;
+	}
+
+	Assert(entry->docPartsSent < entry->docPartsCount);
+
+	const auto partBytes = readDocPart(entry);
+	if (partBytes.isEmpty()) {
+		failed(itemId);
+		return SendResult::Failed;
+	}
+	const auto part = entry->docPartsSent++;
+	++entry->docPartsWaiting;
+
+	const auto send = [&](auto &&request, bool big) {
+		sendPreparedRequest(std::move(request), {
+			.itemId = itemId,
+			.bytes = partBytes,
+			.part = part,
+			.dcIndex = dcIndex,
+			.docPart = true,
+			.bigPart = big,
+		});
+	};
+	if (entry->docSize > kUseBigFilesFrom) {
+		send(MTPupload_SaveBigFilePart(
+			MTP_long(entry->file->id),
+			MTP_int(part),
+			MTP_int(entry->docPartsCount),
+			MTP_bytes(partBytes)
+		), true);
+	} else {
+		send(MTPupload_SaveFilePart(
+			MTP_long(entry->file->id),
+			MTP_int(part),
+			MTP_bytes(partBytes)
+		), false);
+	}
+	return SendResult::Success;
+}
+
+auto Uploader::sendSlicedPart(not_null<Entry*> entry, uchar dcIndex)
+-> SendResult {
+	const auto itemId = entry->itemId;
+	const auto alreadySent = _sentPerDcIndex[dcIndex];
+	const auto willBeSent = entry->parts->at(entry->partsSent).size();
+	if (alreadySent + willBeSent >= kMaxUploadPerSession) {
+		return SendResult::DcIndexFull;
+	}
+
+	++entry->partsWaiting;
+	const auto index = entry->partsSent++;
+	const auto partBytes = entry->parts->at(index);
+	sendPreparedRequest(MTPupload_SaveFilePart(
+		MTP_long(entry->partsOfId),
+		MTP_int(index),
+		MTP_bytes(partBytes)
+	), {
+		.itemId = itemId,
+		.bytes = partBytes,
+		.dcIndex = dcIndex,
+	});
+	return SendResult::Success;
+}
+
+void Uploader::maybeSend() {
 	const auto stopping = _stopSessionsTimer.isActive();
 	if (_queue.empty()) {
 		if (!stopping) {
@@ -404,111 +590,35 @@ void Uploader::maybeSendNext() {
 		return;
 	} else if (_pausedId) {
 		return;
-	}
-
-	if (stopping) {
+	} else if (stopping) {
 		_stopSessionsTimer.cancel();
 	}
 
-	auto todc = 0;
-	if (_sentPerDcIndex.size() < 2) {
-		todc = int(_sentPerDcIndex.size());
-		_sentPerDcIndex.resize(todc + 1);
-	} else {
-		const auto min = ranges::min_element(_sentPerDcIndex);
-		todc = int(min - begin(_sentPerDcIndex));
-	}
-	const auto alreadySent = _sentPerDcIndex[todc];
-
-	const auto entry = [&]() -> Entry* {
-		for (auto i = begin(_queue); i != end(_queue); ++i) {
-			if (i->partsSent < i->parts->size()
-				|| i->docPartsSent < i->docPartsCount) {
-				return &*i;
+	auto usedDcIndices = base::flat_set<uchar>();
+	while (true) {
+		const auto maybeDcIndex = chooseDcIndexForNextRequest(usedDcIndices);
+		if (!maybeDcIndex.has_value()) {
+			break;
+		}
+		const auto dcIndex = *maybeDcIndex;
+		while (true) {
+			const auto entry = chooseEntryForNextRequest();
+			if (!entry) {
+				return;
 			}
+			const auto result = sendPart(entry, dcIndex);
+			if (result == SendResult::DcIndexFull) {
+				return;
+			} else if (result == SendResult::Success) {
+				break;
+			}
+			// If this entry failed, we try the next one.
 		}
-		return nullptr;
-	}();
-	if (!entry) {
-		return;
+		usedDcIndices.emplace(dcIndex);
 	}
-
-	const auto itemId = entry->itemId;
-	if (entry->partsSent >= entry->parts->size()) {
-		const auto willProbablyBeSent = entry->docPartSize;
-		if (alreadySent + willProbablyBeSent >= kMaxUploadPerSession) {
-			return;
-		}
-
-		Assert(entry->docPartsSent < entry->docPartsCount);
-
-		const auto partBytes = readDocPart(entry);
-		if (partBytes.isEmpty()) {
-			failed(itemId);
-			return;
-		}
-		const auto index = entry->docPartsSent++;
-		++entry->docPartsWaiting;
-
-		mtpRequestId requestId;
-		if (entry->docSize > kUseBigFilesFrom) {
-			requestId = _api->request(MTPupload_SaveBigFilePart(
-				MTP_long(entry->file->id),
-				MTP_int(index),
-				MTP_int(entry->docPartsCount),
-				MTP_bytes(partBytes)
-			)).done([=](const MTPBool &result, mtpRequestId requestId) {
-				partLoaded(result, requestId);
-			}).fail([=](const MTP::Error &error, mtpRequestId requestId) {
-				partFailed(error, requestId);
-			}).toDC(MTP::uploadDcId(todc)).send();
-		} else {
-			requestId = _api->request(MTPupload_SaveFilePart(
-				MTP_long(entry->file->id),
-				MTP_int(index),
-				MTP_bytes(partBytes)
-			)).done([=](const MTPBool &result, mtpRequestId requestId) {
-				partLoaded(result, requestId);
-			}).fail([=](const MTP::Error &error, mtpRequestId requestId) {
-				partFailed(error, requestId);
-			}).toDC(MTP::uploadDcId(todc)).send();
-		}
-		_requests.emplace(requestId, Request{
-			.itemId = itemId,
-			.sent = crl::now(),
-			.bytes = partBytes,
-			.dcIndex = todc,
-			.docPart = true,
-		});
-		_sentPerDcIndex[todc] += int(partBytes.size());
-	} else {
-		const auto willBeSent = entry->parts->at(entry->partsSent).size();
-		if (alreadySent + willBeSent >= kMaxUploadPerSession) {
-			return;
-		}
-
-		++entry->partsWaiting;
-		const auto index = entry->partsSent++;
-		const auto partBytes = entry->parts->at(index);
-		const auto requestId = _api->request(MTPupload_SaveFilePart(
-			MTP_long(entry->partsOfId),
-			MTP_int(index),
-			MTP_bytes(partBytes)
-		)).done([=](const MTPBool &result, mtpRequestId requestId) {
-			partLoaded(result, requestId);
-		}).fail([=](const MTP::Error &error, mtpRequestId requestId) {
-			partFailed(error, requestId);
-		}).toDC(MTP::uploadDcId(todc)).send();
-
-		_requests.emplace(requestId, Request{
-			.itemId = itemId,
-			.sent = crl::now(),
-			.bytes = partBytes,
-			.dcIndex = todc,
-		});
-		_sentPerDcIndex[todc] += int(partBytes.size());
+	if (!usedDcIndices.empty()) {
+		_nextTimer.callOnce(kUploadRequestInterval);
 	}
-	_nextTimer.callOnce(kUploadRequestInterval);
 }
 
 void Uploader::cancel(FullMsgId itemId) {
@@ -529,7 +639,7 @@ void Uploader::pause(FullMsgId itemId) {
 
 void Uploader::unpause() {
 	_pausedId = FullMsgId();
-	maybeSendNext();
+	maybeSend();
 }
 
 void Uploader::cancelRequests(FullMsgId itemId) {
@@ -543,6 +653,11 @@ void Uploader::cancelRequests(FullMsgId itemId) {
 			++i;
 		}
 	}
+	_pendingFromRemovedDcIndices.erase(ranges::remove(
+		_pendingFromRemovedDcIndices,
+		itemId,
+		&Request::itemId
+	), end(_pendingFromRemovedDcIndices));
 }
 
 void Uploader::cancelAllRequests() {
@@ -582,19 +697,48 @@ void Uploader::partLoaded(const MTPBool &result, mtpRequestId requestId) {
 	Assert(i != end(_queue));
 	auto &entry = *i;
 
+	const auto now = crl::now();
+	const auto duration = now - request.sent;
+	const auto fast = (duration < kFastRequestThreshold);
+	const auto slowish = !fast;
+	const auto slow = (duration >= kSlowRequestThreshold);
+
+	if (slowish) {
+		_dcIndicesWithFastRequests.clear();
+		if (slow) {
+			const auto elapsed = (now - _latestDcIndexRemoved);
+			const auto remove = (elapsed >= kWaitForNormalizeTimeout);
+			if (remove && _sentPerDcIndex.size() > 1) {
+				DEBUG_LOG(("Uploader: Slow request, removing dc index."));
+				removeDcIndex();
+				_latestDcIndexRemoved = now;
+			} else {
+				DEBUG_LOG(("Uploader: Slow request, clear fast records."));
+			}
+		} else {
+			DEBUG_LOG(("Uploader: Slow-ish request, clear fast records."));
+		}
+	} else if (request.sent > _latestDcIndexAdded) {
+		if (_dcIndicesWithFastRequests.emplace(request.dcIndex).second) {
+			DEBUG_LOG(("Uploader: Mark %1 of %2 as fast."
+				).arg(request.dcIndex
+				).arg(_sentPerDcIndex.size()));
+		}
+	}
+
 	if (request.docPart) {
 		--entry.docPartsWaiting;
 		entry.docSentSize += bytes;
 	} else {
 		--entry.partsWaiting;
-		entry.partsSentSize += bytes;
+		entry.sentSize += bytes;
 	}
 
 	if (entry.file->type == SendMediaType::Photo) {
 		const auto photo = session().data().photo(entry.file->id);
 		if (photo->uploading()) {
 			photo->uploadingData->size = entry.file->partssize;
-			photo->uploadingData->offset = entry.partsSentSize;
+			photo->uploadingData->offset = entry.sentSize;
 		}
 		_photoProgress.fire_copy(itemId);
 	} else if (entry.file->type == SendMediaType::File
@@ -610,7 +754,7 @@ void Uploader::partLoaded(const MTPBool &result, mtpRequestId requestId) {
 	} else if (entry.file->type == SendMediaType::Secure) {
 		_secureProgress.fire_copy({
 			.fullId = itemId,
-			.offset = entry.partsSentSize,
+			.offset = entry.sentSize,
 			.size = entry.file->partssize,
 		});
 	}
@@ -621,7 +765,29 @@ void Uploader::partLoaded(const MTPBool &result, mtpRequestId requestId) {
 	if (!_queue.empty() && itemId == _queue.front().itemId) {
 		maybeFinishFront();
 	}
-	maybeSendNext();
+	maybeSend();
+}
+
+void Uploader::removeDcIndex() {
+	Expects(_sentPerDcIndex.size() > 1);
+
+	const auto dcIndex = int(_sentPerDcIndex.size()) - 1;
+	for (auto i = begin(_requests); i != end(_requests);) {
+		if (i->second.dcIndex == dcIndex) {
+			const auto bytes = int(i->second.bytes.size());
+			_sentPerDcIndex[dcIndex] -= bytes;
+			_api->request(i->first).cancel();
+			_pendingFromRemovedDcIndices.push_back(std::move(i->second));
+			i = _requests.erase(i);
+		} else {
+			++i;
+		}
+	}
+	Assert(_sentPerDcIndex.back() == 0);
+	_sentPerDcIndex.pop_back();
+	_dcIndicesWithFastRequests.remove(dcIndex);
+	_api->instance().stopSession(MTP::uploadDcId(dcIndex));
+	DEBUG_LOG(("Uploader: Removed dc index %1.").arg(dcIndex));
 }
 
 void Uploader::maybeFinishFront() {
diff --git a/Telegram/SourceFiles/storage/file_upload.h b/Telegram/SourceFiles/storage/file_upload.h
index f4fced340..6f87f6a56 100644
--- a/Telegram/SourceFiles/storage/file_upload.h
+++ b/Telegram/SourceFiles/storage/file_upload.h
@@ -103,8 +103,30 @@ private:
 	struct Entry;
 	struct Request;
 
+	enum class SendResult : uchar {
+		Success,
+		Failed,
+		DcIndexFull,
+	};
+
+	void maybeSend();
+	[[nodiscard]] bool canAddDcIndex() const;
+	[[nodiscard]] std::optional<uchar> chooseDcIndexForNextRequest(
+		const base::flat_set<uchar> &used);
+	[[nodiscard]] Entry *chooseEntryForNextRequest();
+	[[nodiscard]] SendResult sendPart(not_null<Entry*> entry, uchar dcIndex);
+	[[nodiscard]] auto sendPendingPart(not_null<Entry*> entry, uchar dcIndex)
+		-> SendResult;
+	[[nodiscard]] auto sendDocPart(not_null<Entry*> entry, uchar dcIndex)
+		-> SendResult;
+	[[nodiscard]] auto sendSlicedPart(not_null<Entry*> entry, uchar dcIndex)
+		-> SendResult;
 	[[nodiscard]] QByteArray readDocPart(not_null<Entry*> entry);
-	void maybeSendNext();
+	void removeDcIndex();
+
+	template <typename Prepared>
+	void sendPreparedRequest(Prepared &&prepared, Request &&request);
+
 	void maybeFinishFront();
 	void finishFront();
 
@@ -135,6 +157,12 @@ private:
 	base::flat_map<mtpRequestId, Request> _requests;
 	std::vector<int> _sentPerDcIndex;
 
+	// Fast requests since the latest dc index addition.
+	base::flat_set<uchar> _dcIndicesWithFastRequests;
+	crl::time _latestDcIndexAdded = 0;
+	crl::time _latestDcIndexRemoved = 0;
+	std::vector<Request> _pendingFromRemovedDcIndices;
+
 	FullMsgId _pausedId;
 	base::Timer _nextTimer, _stopSessionsTimer;