diff --git a/builds/install/misc/firebird.conf b/builds/install/misc/firebird.conf
index 98959d4b8dd..eb80895a9a3 100644
--- a/builds/install/misc/firebird.conf
+++ b/builds/install/misc/firebird.conf
@@ -1005,6 +1005,12 @@
 # CPU 1 and CPU 2, the value is 3. To use CPU 2 and CPU 3, the value
 # is 6. The default value is 0 - no affinity will be set.
 #
+# About systems with heterogeneous (Efficient\Performance) set of cores:
+# on Windows 10 and later, if affinity is not set nor by CpuAffinityMask, 
+# nor by the caller process, then server tries to exclude efficient cores
+# from own affinity mask. I.e. default affinity mask includes performance
+# cores only.
+#
 # Type: integer
 #
 #CpuAffinityMask = 0
diff --git a/src/common/os/os_utils.h b/src/common/os/os_utils.h
index 3288e1e971f..bbdc2f1c459 100644
--- a/src/common/os/os_utils.h
+++ b/src/common/os/os_utils.h
@@ -358,6 +358,10 @@ namespace os_utils
 
 #endif	// WIN_NT
 
+#ifdef WIN_NT
+	void setDefaultAffinity();
+#endif
+
 	class CtrlCHandler
 	{
 	public:
diff --git a/src/common/os/win32/os_utils.cpp b/src/common/os/win32/os_utils.cpp
index 85d7c1e1181..15fb64f1b8b 100644
--- a/src/common/os/win32/os_utils.cpp
+++ b/src/common/os/win32/os_utils.cpp
@@ -29,6 +29,7 @@
 
 #include "../common/classes/array.h"
 #include "../common/classes/init.h"
+#include "../common/classes/GenericMap.h"
 #include "../common/gdsassert.h"
 #include "../common/os/guid.h"
 #include "../common/os/os_utils.h"
@@ -560,6 +561,65 @@ void getUniqueFileId(HANDLE fd, UCharBuffer& id)
 		   sizeof(file_info.nFileIndexLow));
 }
 
+void setDefaultAffinity()
+{
+	HANDLE hCurrProc = GetCurrentProcess();
+
+	DWORD_PTR procMask, sysMask, newMask;
+	GetProcessAffinityMask(hCurrProc, &procMask, &sysMask);
+
+	// Don't change affinity if it was set by caller process
+	if (procMask != sysMask)
+		return;
+
+	newMask = sysMask;
+
+	DWORD len = 0;
+
+	if (!GetLogicalProcessorInformationEx(RelationProcessorCore, nullptr, &len))
+	{
+		if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+			return;
+	}
+
+ 	HalfStaticArray<UCHAR, 1024, SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX> buff;
+	auto p = buff.getBuffer(len);
+	auto const end = p + len;
+	auto pSLPI = reinterpret_cast<PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX>(p);
+
+	if (!GetLogicalProcessorInformationEx(RelationProcessorCore, pSLPI, &len))
+		return;
+
+	// Efficiency Class to Cores map
+	GenericMap<NonPooledPair<int, DWORD_PTR>> effClassMasks;
+
+	while (p < end)
+	{
+		if (pSLPI->Relationship == RelationProcessorCore)
+		{
+			DWORD_PTR coreMask = 0;
+			for (size_t i = 0; i < pSLPI->Processor.GroupCount; i++)
+				coreMask |= pSLPI->Processor.GroupMask[i].Mask;
+
+			DWORD_PTR* pMask = effClassMasks.get(pSLPI->Processor.EfficiencyClass);
+			if (!pMask)
+				effClassMasks.put(pSLPI->Processor.EfficiencyClass, coreMask);
+			else
+				*pMask |= coreMask;
+		}
+
+		p += pSLPI->Size;
+		pSLPI = reinterpret_cast<PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX>(p);
+	}
+
+	// Exclude efficient cores, i.e. cores with lowest efficient class
+	if (effClassMasks.count() > 1)
+		newMask &= ~(*effClassMasks.begin()).second;
+
+	if (newMask && newMask != procMask)
+		SetProcessAffinityMask(hCurrProc, newMask);
+}
+
 
 /// class CtrlCHandler
 
diff --git a/src/remote/server/os/win32/srvr_w32.cpp b/src/remote/server/os/win32/srvr_w32.cpp
index be7a705cdd3..93ae0925beb 100644
--- a/src/remote/server/os/win32/srvr_w32.cpp
+++ b/src/remote/server/os/win32/srvr_w32.cpp
@@ -219,6 +219,8 @@ int WINAPI WinMain(HINSTANCE hThisInst, HINSTANCE /*hPrevInst*/, LPSTR lpszArgs,
 	const DWORD_PTR affinity = Config::getCpuAffinityMask();
 	if (affinity)
 		SetProcessAffinityMask(GetCurrentProcess(), affinity);
+	else
+		os_utils::setDefaultAffinity();
 
 	protocol_inet[0] = 0;