diff --git a/include/freerdp/server/shadow.h b/include/freerdp/server/shadow.h
index baaac3e5c..0620cf626 100644
--- a/include/freerdp/server/shadow.h
+++ b/include/freerdp/server/shadow.h
@@ -113,7 +113,9 @@ struct rdp_shadow_server
 	int monitorCount; \
 	MONITOR_DEF monitors[16]; \
 	MONITOR_DEF virtualScreen; \
+	HANDLE updateEvent; \
 	REGION16 invalidRegion; \
+	SYNCHRONIZATION_BARRIER barrier; \
 	\
 	pfnShadowSubsystemInit Init; \
 	pfnShadowSubsystemUninit Uninit; \
diff --git a/server/shadow/Win/win_shadow.c b/server/shadow/Win/win_shadow.c
index e9e746675..46a8fa636 100644
--- a/server/shadow/Win/win_shadow.c
+++ b/server/shadow/Win/win_shadow.c
@@ -1072,6 +1072,8 @@ void win_shadow_subsystem_free(winShadowSubsystem* subsystem)
 
 	region16_uninit(&(subsystem->invalidRegion));
 
+	CloseHandle(subsystem->updateEvent);
+
 	free(subsystem);
 }
 
@@ -1086,6 +1088,8 @@ winShadowSubsystem* win_shadow_subsystem_new(rdpShadowServer* server)
 
 	subsystem->server = server;
 
+	subsystem->updateEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+
 	region16_init(&(subsystem->invalidRegion));
 
 	subsystem->Init = (pfnShadowSubsystemInit) win_shadow_subsystem_init;
diff --git a/server/shadow/X11/x11_shadow.c b/server/shadow/X11/x11_shadow.c
index a18ab8b7c..a96d55d31 100644
--- a/server/shadow/X11/x11_shadow.c
+++ b/server/shadow/X11/x11_shadow.c
@@ -187,6 +187,7 @@ int x11_shadow_invalidate_region(x11ShadowSubsystem* subsystem, int x, int y, in
 
 int x11_shadow_screen_grab(x11ShadowSubsystem* subsystem)
 {
+	int count;
 	int status;
 	int x, y;
 	int width, height;
@@ -200,18 +201,18 @@ int x11_shadow_screen_grab(x11ShadowSubsystem* subsystem)
 	surface = server->surface;
 	screen = server->screen;
 
-	XLockDisplay(subsystem->display);
-
 	if (subsystem->use_xshm)
 	{
+		XLockDisplay(subsystem->display);
+
 		XCopyArea(subsystem->display, subsystem->root_window, subsystem->fb_pixmap,
 				subsystem->xshm_gc, 0, 0, subsystem->width, subsystem->height, 0, 0);
 
 		XSync(subsystem->display, False);
 
-		image = subsystem->fb_image;
+		XUnlockDisplay(subsystem->display);
 
-		EnterCriticalSection(&(screen->lock));
+		image = subsystem->fb_image;
 
 		status = shadow_capture_compare(surface->data, surface->scanline, surface->width, surface->height,
 				(BYTE*) image->data, image->bytes_per_line, &invalidRect);
@@ -230,20 +231,29 @@ int x11_shadow_screen_grab(x11ShadowSubsystem* subsystem)
 
 			region16_union_rect(&(subsystem->invalidRegion), &(subsystem->invalidRegion), &invalidRect);
 
-			if (subsystem->SurfaceUpdate)
-				subsystem->SurfaceUpdate((rdpShadowSubsystem*) subsystem, &(subsystem->invalidRegion));
+			count = ArrayList_Count(server->clients);
+
+			InitializeSynchronizationBarrier(&(subsystem->barrier), count + 1, -1);
+
+			SetEvent(subsystem->updateEvent);
+
+			EnterSynchronizationBarrier(&(subsystem->barrier), 0);
+
+			DeleteSynchronizationBarrier(&(subsystem->barrier));
+
+			ResetEvent(subsystem->updateEvent);
 
 			region16_clear(&(subsystem->invalidRegion));
 		}
-
-		LeaveCriticalSection(&(screen->lock));
 	}
 	else
 	{
+		XLockDisplay(subsystem->display);
+
 		image = XGetImage(subsystem->display, subsystem->root_window,
 				0, 0, subsystem->width, subsystem->height, AllPlanes, ZPixmap);
 
-		EnterCriticalSection(&(screen->lock));
+		XUnlockDisplay(subsystem->display);
 
 		status = shadow_capture_compare(surface->data, surface->scanline, surface->width, surface->height,
 				(BYTE*) image->data, image->bytes_per_line, &invalidRect);
@@ -262,19 +272,24 @@ int x11_shadow_screen_grab(x11ShadowSubsystem* subsystem)
 
 			region16_union_rect(&(subsystem->invalidRegion), &(subsystem->invalidRegion), &invalidRect);
 
-			if (subsystem->SurfaceUpdate)
-				subsystem->SurfaceUpdate((rdpShadowSubsystem*) subsystem, &(subsystem->invalidRegion));
+			count = ArrayList_Count(server->clients);
+
+			InitializeSynchronizationBarrier(&(subsystem->barrier), count + 1, -1);
+
+			SetEvent(subsystem->updateEvent);
+
+			EnterSynchronizationBarrier(&(subsystem->barrier), 0);
+
+			DeleteSynchronizationBarrier(&(subsystem->barrier));
+
+			ResetEvent(subsystem->updateEvent);
 
 			region16_clear(&(subsystem->invalidRegion));
 		}
 
-		LeaveCriticalSection(&(screen->lock));
-
 		XDestroyImage(image);
 	}
 
-	XUnlockDisplay(subsystem->display);
-
 	return 1;
 }
 
@@ -299,7 +314,7 @@ void* x11_shadow_subsystem_thread(x11ShadowSubsystem* subsystem)
 	events[nCount++] = StopEvent;
 	events[nCount++] = subsystem->event;
 
-	fps = 24;
+	fps = 16;
 	dwInterval = 1000 / fps;
 	frameTime = GetTickCount64() + dwInterval;
 
@@ -749,6 +764,8 @@ void x11_shadow_subsystem_free(x11ShadowSubsystem* subsystem)
 
 	region16_uninit(&(subsystem->invalidRegion));
 
+	CloseHandle(subsystem->updateEvent);
+
 	free(subsystem);
 }
 
@@ -763,6 +780,8 @@ x11ShadowSubsystem* x11_shadow_subsystem_new(rdpShadowServer* server)
 
 	subsystem->server = server;
 
+	subsystem->updateEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+
 	region16_init(&(subsystem->invalidRegion));
 
 	subsystem->Init = (pfnShadowSubsystemInit) x11_shadow_subsystem_init;
diff --git a/server/shadow/shadow_client.c b/server/shadow/shadow_client.c
index e3f08a44e..7bf20441b 100644
--- a/server/shadow/shadow_client.c
+++ b/server/shadow/shadow_client.c
@@ -613,17 +613,13 @@ int shadow_client_surface_update(rdpShadowClient* client, REGION16* region)
 
 void* shadow_client_thread(rdpShadowClient* client)
 {
-	int fps;
 	DWORD status;
 	DWORD nCount;
-	UINT64 cTime;
-	DWORD dwTimeout;
-	DWORD dwInterval;
-	UINT64 frameTime;
 	HANDLE events[32];
 	HANDLE StopEvent;
 	HANDLE ClientEvent;
 	HANDLE ChannelEvent;
+	HANDLE UpdateEvent;
 	freerdp_peer* peer;
 	rdpSettings* settings;
 	rdpShadowServer* server;
@@ -651,11 +647,8 @@ void* shadow_client_thread(rdpShadowClient* client)
 			shadow_client_surface_frame_acknowledge;
 	peer->update->SuppressOutput = (pSuppressOutput) shadow_client_suppress_output;
 
-	fps = 16;
-	dwInterval = 1000 / fps;
-	frameTime = GetTickCount64() + dwInterval;
-
 	StopEvent = client->StopEvent;
+	UpdateEvent = subsystem->updateEvent;
 	ClientEvent = peer->GetEventHandle(peer);
 	ChannelEvent = WTSVirtualChannelManagerGetEventHandle(client->vcm);
 
@@ -663,19 +656,43 @@ void* shadow_client_thread(rdpShadowClient* client)
 	{
 		nCount = 0;
 		events[nCount++] = StopEvent;
+		events[nCount++] = UpdateEvent;
 		events[nCount++] = ClientEvent;
 		events[nCount++] = ChannelEvent;
 
-		cTime = GetTickCount64();
-		dwTimeout = (DWORD) ((cTime > frameTime) ? 0 : frameTime - cTime);
+		status = WaitForMultipleObjects(nCount, events, FALSE, INFINITE);
 
-		status = WaitForMultipleObjects(nCount, events, FALSE, dwTimeout);
-
-		if (WaitForSingleObject(client->StopEvent, 0) == WAIT_OBJECT_0)
+		if (WaitForSingleObject(StopEvent, 0) == WAIT_OBJECT_0)
 		{
+			if (WaitForSingleObject(UpdateEvent, 0) == WAIT_OBJECT_0)
+			{
+				EnterSynchronizationBarrier(&(subsystem->barrier), 0);
+			}
+
 			break;
 		}
 
+		if (WaitForSingleObject(UpdateEvent, 0) == WAIT_OBJECT_0)
+		{
+			if (client->activated)
+			{
+				int index;
+				int numRects = 0;
+				const RECTANGLE_16* rects;
+
+				rects = region16_rects(&(subsystem->invalidRegion), &numRects);
+
+				for (index = 0; index < numRects; index++)
+				{
+					region16_union_rect(&(client->invalidRegion), &(client->invalidRegion), &rects[index]);
+				}
+
+				shadow_client_send_surface_update(client);
+			}
+
+			EnterSynchronizationBarrier(&(subsystem->barrier), 0);
+		}
+
 		if (WaitForSingleObject(ClientEvent, 0) == WAIT_OBJECT_0)
 		{
 			if (!peer->CheckFileDescriptor(peer))
@@ -693,22 +710,6 @@ void* shadow_client_thread(rdpShadowClient* client)
 				break;
 			}
 		}
-
-		if ((status == WAIT_TIMEOUT) || (GetTickCount64() > frameTime))
-		{
-			if (client->activated)
-			{
-				EnterCriticalSection(&(screen->lock));
-
-				shadow_client_send_surface_update(client);
-
-				LeaveCriticalSection(&(screen->lock));
-			}
-
-			fps = encoder->fps;
-			dwInterval = 1000 / fps;
-			frameTime += dwInterval;
-		}
 	}
 
 	peer->Disconnect(peer);