diff --git a/Utilities/Log.cpp b/Utilities/Log.cpp
index 3f7d283493..21e52a69dc 100644
--- a/Utilities/Log.cpp
+++ b/Utilities/Log.cpp
@@ -69,10 +69,17 @@ namespace logs
 		::HANDLE m_fmap;
 #endif
 		uchar* m_fptr{};
+		z_stream m_zs{};
+		semaphore<> m_m;
 
 		alignas(128) atomic_t<u64> m_buf{0}; // MSB (40 bit): push begin, LSB (24 bis): push size
 		alignas(128) atomic_t<u64> m_out{0}; // Amount of bytes written to file
 
+		uchar m_zout[65536];
+
+		// Write buffered logs immediately
+		bool flush(u64 bufv);
+
 	public:
 		file_writer(const std::string& name);
 
@@ -355,7 +362,10 @@ logs::file_writer::file_writer(const std::string& name)
 		m_fout.open(log_name, fs::rewrite);
 
 		// Compressed log
-		m_fout2.open(log_name + ".gz", fs::rewrite);
+		if (!m_fout2.open(log_name + ".gz", fs::rewrite) || deflateInit2(&m_zs, 9, Z_DEFLATED, 16 + 15, 9, Z_DEFAULT_STRATEGY) != Z_OK)
+		{
+			m_fout2.close();
+		}
 	}
 	catch (...)
 	{
@@ -366,15 +376,6 @@ logs::file_writer::file_writer(const std::string& name)
 	{
 		thread_ctrl::set_native_priority(-1);
 
-		z_stream zs{};
-		uchar out[65536];
-		bool zs_init = true;
-		if (!m_fout2 || deflateInit2(&zs, 9, Z_DEFLATED, 16 + 15, 9, Z_DEFAULT_STRATEGY) != Z_OK)
-		{
-			zs_init = false;
-			m_fout2.close();
-		}
-
 		while (true)
 		{
 			const u64 bufv = m_buf;
@@ -386,42 +387,9 @@ logs::file_writer::file_writer(const std::string& name)
 				continue;
 			}
 
-			const u64 st = +m_out;
-			const u64 end = std::min<u64>((st + s_log_size) & ~(s_log_size - 1), bufv >> 24);
-
-			if (end > st)
+			if (!flush(bufv))
 			{
-				const u64 size = end - st;
-
-				if (m_fout && m_fout.write(m_fptr + st % s_log_size, size) != size)
-				{
-					m_fout.close();
-				}
-
-				if (m_fout2)
-				{
-					zs.avail_in = size;
-					zs.next_in = m_fptr + st % s_log_size;
-
-					do
-					{
-						zs.avail_out = sizeof(out);
-						zs.next_out = out;
-
-						if (deflate(&zs, Z_NO_FLUSH) == Z_STREAM_ERROR || m_fout2.write(out, sizeof(out) - zs.avail_out) != sizeof(out) - zs.avail_out)
-						{
-							m_fout2.close();
-							break;
-						}
-					}
-					while (zs.avail_out == 0);
-				}
-
-				m_out += end - st;
-			}
-			else
-			{
-				if (st == -1)
+				if (m_out == -1)
 				{
 					break;
 				}
@@ -429,29 +397,6 @@ logs::file_writer::file_writer(const std::string& name)
 				std::this_thread::sleep_for(10ms);
 			}
 		}
-
-		if (zs_init)
-		{
-			if (m_fout2)
-			{
-				zs.avail_in = 0;
-				zs.next_in = nullptr;
-
-				do
-				{
-					zs.avail_out = sizeof(out);
-					zs.next_out = out;
-
-					if (deflate(&zs, Z_FINISH) == Z_STREAM_ERROR || m_fout2.write(out, sizeof(out) - zs.avail_out) != sizeof(out) - zs.avail_out)
-					{
-						break;
-					}
-				}
-				while (zs.avail_out == 0);
-			}
-
-			deflateEnd(&zs);
-		}
 	});
 }
 
@@ -466,6 +411,26 @@ logs::file_writer::~file_writer()
 	m_out = -1;
 	m_writer.join();
 
+	if (m_fout2)
+	{
+		m_zs.avail_in = 0;
+		m_zs.next_in  = nullptr;
+
+		do
+		{
+			m_zs.avail_out = sizeof(m_zout);
+			m_zs.next_out  = m_zout;
+
+			if (deflate(&m_zs, Z_FINISH) == Z_STREAM_ERROR || m_fout2.write(m_zout, sizeof(m_zout) - m_zs.avail_out) != sizeof(m_zout) - m_zs.avail_out)
+			{
+				break;
+			}
+		}
+		while (m_zs.avail_out == 0);
+
+		deflateEnd(&m_zs);
+	}
+
 #ifdef _WIN32
 	UnmapViewOfFile(m_fptr);
 	CloseHandle(m_fmap);
@@ -474,17 +439,67 @@ logs::file_writer::~file_writer()
 #endif
 }
 
+bool logs::file_writer::flush(u64 bufv)
+{
+	semaphore_lock lock(m_m);
+
+	const u64 st  = +m_out;
+	const u64 end = std::min<u64>((st + s_log_size) & ~(s_log_size - 1), bufv >> 24);
+
+	if (end > st)
+	{
+		// Avoid writing too big fragments
+		const u64 size = std::min<u64>(end - st, sizeof(m_zout) / 2);
+
+		// Write uncompressed
+		if (m_fout && m_fout.write(m_fptr + st % s_log_size, size) != size)
+		{
+			m_fout.close();
+		}
+
+		// Write compressed
+		if (m_fout2)
+		{
+			m_zs.avail_in = size;
+			m_zs.next_in  = m_fptr + st % s_log_size;
+
+			do
+			{
+				m_zs.avail_out = sizeof(m_zout);
+				m_zs.next_out  = m_zout;
+
+				if (deflate(&m_zs, Z_NO_FLUSH) == Z_STREAM_ERROR || m_fout2.write(m_zout, sizeof(m_zout) - m_zs.avail_out) != sizeof(m_zout) - m_zs.avail_out)
+				{
+					deflateEnd(&m_zs);
+					m_fout2.close();
+					break;
+				}
+			}
+			while (m_zs.avail_out == 0);
+		}
+
+		m_out += size;
+		return true;
+	}
+
+	return false;
+}
+
 void logs::file_writer::log(logs::level sev, const char* text, std::size_t size)
 {
-	while (true)
+	// TODO: write bigger fragment directly in blocking manner
+	while (size && size <= 0xffffff)
 	{
+		u64 bufv;
+
 		const auto pos = m_buf.atomic_op([&](u64& v) -> uchar*
 		{
 			const u64 v1 = v >> 24;
 			const u64 v2 = v & 0xffffff;
 
-			if (v2 + size > 0xffffff || v1 + v2 + size >= m_out + s_log_size)
+			if (UNLIKELY(v2 + size > 0xffffff || v1 + v2 + size >= m_out + s_log_size))
 			{
+				bufv = v;
 				return nullptr;
 			}
 
@@ -494,7 +509,16 @@ void logs::file_writer::log(logs::level sev, const char* text, std::size_t size)
 
 		if (UNLIKELY(!pos))
 		{
-			std::this_thread::yield();
+			if ((bufv & 0xffffff) + size > 0xffffff || bufv & 0xffffff)
+			{
+				// Concurrency limit reached
+				std::this_thread::yield();
+			}
+			else
+			{
+				// Queue is full, need to write out
+				flush(bufv);
+			}
 			continue;
 		}