diff --git a/4J.Render/4J_Render.cpp b/4J.Render/4J_Render.cpp
index 571a3d171..351532d4f 100644
--- a/4J.Render/4J_Render.cpp
+++ b/4J.Render/4J_Render.cpp
@@ -94,8 +94,8 @@ void C4JRender::Initialise()
     }
 
     glfwMakeContextCurrent(s_window);
-    glfwSwapInterval(0);  // vsync
-
+    glfwSwapInterval(1);  // vsync
+    
     // Keep viewport in sync with OS-driven window resizes.
     glfwSetFramebufferSizeCallback(s_window, onFramebufferResize);
 
diff --git a/Minecraft.Client/Platform/Common/Consoles_App.cpp b/Minecraft.Client/Platform/Common/Consoles_App.cpp
index 5268792f2..9c4974493 100644
--- a/Minecraft.Client/Platform/Common/Consoles_App.cpp
+++ b/Minecraft.Client/Platform/Common/Consoles_App.cpp
@@ -631,7 +631,7 @@ void CMinecraftApp::InitGameSettings()
 		// 4J-PB - don't cause an options write to happen here
 		SetDefaultOptions(pProfileSettings,i,false);
 #else
-		// Linux (and any other platform): profile data is zero-initialised, so explicitly apply defaults
+		// 4jcrqaft: Linux (and any other platform): profile data is zero-initialised, so explicitly apply defaults
 		C_4JProfile::PROFILESETTINGS *pProfileSettings=ProfileManager.GetDashboardProfileSettings(i);
 		memset(pProfileSettings,0,sizeof(C_4JProfile::PROFILESETTINGS));
 		SetDefaultOptions(pProfileSettings,i);
diff --git a/Minecraft.Client/Rendering/EntityRenderers/ItemInHandRenderer.cpp b/Minecraft.Client/Rendering/EntityRenderers/ItemInHandRenderer.cpp
index d630d139a..bdefd3748 100644
--- a/Minecraft.Client/Rendering/EntityRenderers/ItemInHandRenderer.cpp
+++ b/Minecraft.Client/Rendering/EntityRenderers/ItemInHandRenderer.cpp
@@ -311,6 +311,8 @@ void ItemInHandRenderer::renderItem3D(Tesselator *t, float u0, float v0, float u
 
 void ItemInHandRenderer::render(float a)
 {
+    // 4jcraft: null checks here fix player hand rendering on linux
+    // TOOD: determine why these are null in the first place
     if (!mc->player || !mc->level) return;
 
     float h = oHeight + (height - oHeight) * a;
diff --git a/Minecraft.Client/Rendering/GameRenderer.cpp b/Minecraft.Client/Rendering/GameRenderer.cpp
index 3a135655b..9335fee5b 100644
--- a/Minecraft.Client/Rendering/GameRenderer.cpp
+++ b/Minecraft.Client/Rendering/GameRenderer.cpp
@@ -777,14 +777,14 @@ void GameRenderer::renderItemInHand(float a, int eye)
 	{
 		if (!mc->options->hideGui && !mc->gameMode->isCutScene()) 
 		{
-			//turnOnLightLayer(a); // disable light layer on handrenderer similarly to how it was done on the chunk render (this makes the hand look proper)
+			//turnOnLightLayer(a); // 4jcraft: disable light layer on handrenderer similarly to how it was done on the chunk render (this makes the hand look proper)
 			PIXBeginNamedEvent(0,"Item in hand render");
-			// add null pointer check to itemInHandRenderer to prevent a occasional seg fault
+			// 4jcraft: add null pointer check to itemInHandRenderer to prevent a occasional seg fault
 			if (itemInHandRenderer != nullptr) {
 				itemInHandRenderer->render(a);
 			}
 			PIXEndNamedEvent();
-			//turnOffLightLayer(a); // disable light layer on handrenderer similarly to how it was done on the chunk render (this makes the hand look proper)
+			//turnOffLightLayer(a); // 4jcraft: disable light layer on handrenderer similarly to how it was done on the chunk render (this makes the hand look proper)
 		}
 	}
 	glPopMatrix();
@@ -792,7 +792,7 @@ void GameRenderer::renderItemInHand(float a, int eye)
 	//if (!mc->options->thirdPersonView && !mc->cameraTargetPlayer->isSleeping())
 	if (!localplayer->ThirdPersonView() && !mc->cameraTargetPlayer->isSleeping())
 	{
-		// add null pointer check to itemInHandRenderer to prevent a occasional seg fault
+		// 4jcraft: add null pointer check to itemInHandRenderer to prevent a occasional seg fault
 		if (itemInHandRenderer != nullptr) {
 			itemInHandRenderer->renderScreenEffect(a);
 		}
@@ -1074,7 +1074,7 @@ void GameRenderer::render(float a, bool bFirst)
 	int xMouse = Mouse::getX() * screenWidth / fbw;
 	int yMouse = screenHeight - Mouse::getY() * screenHeight / fbh - 1;
 
-	int maxFps = 0;//getFpsCap(mc->options->framerateLimit);
+	int maxFps = getFpsCap(mc->options->framerateLimit);
 
 	if (mc->level != NULL)
 	{
diff --git a/Minecraft.World/Network/Packets/SetEntityMotionPacket.cpp b/Minecraft.World/Network/Packets/SetEntityMotionPacket.cpp
index cb6d2a42c..6fcf4a4b2 100644
--- a/Minecraft.World/Network/Packets/SetEntityMotionPacket.cpp
+++ b/Minecraft.World/Network/Packets/SetEntityMotionPacket.cpp
@@ -77,7 +77,10 @@ void SetEntityMotionPacket::write(DataOutputStream *dos) //throws IOException
 {
 	if( useBytes )
 	{
-		// Masking the id to 11 bits before writing to account for large entitty ids.
+		// 4jcraft: masking the id to 11 bits before writing to account for entity ids > 4095.
+		// This fixes a connection drop when loading the tutorial world on linux.
+		//
+		// FIXME: find the root cause of this, since there shouldn't be more than 4095 entities.
 		dos->writeShort((id & 0x07FF) | 0x800);
 		dos->writeByte(xa/16);
 		dos->writeByte(ya/16);
@@ -85,7 +88,7 @@ void SetEntityMotionPacket::write(DataOutputStream *dos) //throws IOException
 	}
 	else
 	{
-		// same thing as line 80 here
+		// 4jcraft: same thing as line 80 here
 		dos->writeShort((id & 0x07FF));
 		dos->writeShort(xa);
 		dos->writeShort(ya);