diff --git a/source/blender/compositor/nodes/COM_ViewerNode.cpp b/source/blender/compositor/nodes/COM_ViewerNode.cpp
index db4fd115d73..679589a7ce1 100644
--- a/source/blender/compositor/nodes/COM_ViewerNode.cpp
+++ b/source/blender/compositor/nodes/COM_ViewerNode.cpp
@@ -37,7 +37,7 @@ void ViewerNode::convertToOperations(ExecutionSystem *graph, CompositorContext *
 	Image *image = (Image*)this->getbNode()->id;
 	ImageUser * imageUser = (ImageUser*) this->getbNode()->storage;
 	bNode *editorNode = this->getbNode();
-	if (imageSocket->isConnected() && (editorNode->flag & NODE_DO_OUTPUT)) {
+	if (imageSocket->isConnected()) {
 		ViewerOperation *viewerOperation = new ViewerOperation();
 		viewerOperation->setColorManagement(context->getScene()->r.color_mgt_flag & R_COLOR_MANAGEMENT);
 		viewerOperation->setColorPredivide(context->getScene()->r.color_mgt_flag & R_COLOR_MANAGEMENT_PREDIVIDE);
diff --git a/source/blender/compositor/operations/COM_BlurBaseOperation.cpp b/source/blender/compositor/operations/COM_BlurBaseOperation.cpp
index babea459d6a..2280ee3a435 100644
--- a/source/blender/compositor/operations/COM_BlurBaseOperation.cpp
+++ b/source/blender/compositor/operations/COM_BlurBaseOperation.cpp
@@ -101,7 +101,10 @@ void BlurBaseOperation::deinitExecution()
 
 void BlurBaseOperation::updateSize(MemoryBuffer **memoryBuffers)
 {
-	float result[4];
-	this->getInputSocketReader(1)->read(result, 0, 0, COM_PS_NEAREST, memoryBuffers);
-	this->size = result[0];
+	if (!this->sizeavailable) {
+		float result[4];
+		this->getInputSocketReader(1)->read(result, 0, 0, COM_PS_NEAREST, memoryBuffers);
+		this->size = result[0];
+		this->sizeavailable = true;
+	}
 }
diff --git a/source/blender/compositor/operations/COM_FastGaussianBlurOperation.cpp b/source/blender/compositor/operations/COM_FastGaussianBlurOperation.cpp
index ad8f3b12387..ad58631f2c1 100644
--- a/source/blender/compositor/operations/COM_FastGaussianBlurOperation.cpp
+++ b/source/blender/compositor/operations/COM_FastGaussianBlurOperation.cpp
@@ -26,13 +26,12 @@
 
 FastGaussianBlurOperation::FastGaussianBlurOperation(): BlurBaseOperation()
 {
-	this->iirgaus = false;
+	this->iirgaus = NULL;
 }
 
 void FastGaussianBlurOperation::executePixel(float *color,int x, int y, MemoryBuffer *inputBuffers[], void *data)
 {
 	MemoryBuffer *newData = (MemoryBuffer*)data;
-	
 	newData->read(color, x, y);	
 }
 
@@ -51,10 +50,7 @@ bool FastGaussianBlurOperation::determineDependingAreaOfInterest(rcti *input, Re
 	}
 	else {
 		if (this->iirgaus) {
-			newInput.xmax = input->xmax + (sx);
-			newInput.xmin = input->xmin - (sx);
-			newInput.ymax = input->ymax + (sy);
-			newInput.ymin = input->ymin - (sy);
+			return false;
 		}
 		else {
 			newInput.xmin = 0;
@@ -66,38 +62,51 @@ bool FastGaussianBlurOperation::determineDependingAreaOfInterest(rcti *input, Re
 	}
 }
 
-void *FastGaussianBlurOperation::initializeTileData(rcti *rect, MemoryBuffer **memoryBuffers)
+void FastGaussianBlurOperation::initExecution()
 {
-	MemoryBuffer *newBuf = (MemoryBuffer*)this->inputProgram->initializeTileData(rect, memoryBuffers);
-	MemoryBuffer *copy = newBuf->duplicate();
-	updateSize(memoryBuffers);
-	
-	int c;
-	sx = data->sizex * this->size/2.0f;
-	sy = data->sizey * this->size/2.0f;	
-	this->iirgaus = true;
-	
-	if ((sx == sy) && (sx > 0.f)) {
-		for (c=0; c<COM_NUMBER_OF_CHANNELS; ++c)
-			IIR_gauss(copy, sx, c, 3);
-	}
-	else {
-		if (sx > 0.f) {
-			for (c=0; c<COM_NUMBER_OF_CHANNELS; ++c)
-				IIR_gauss(copy, sx, c, 1);
-		}
-		if (sy > 0.f) {
-			for (c=0; c<COM_NUMBER_OF_CHANNELS; ++c)
-				IIR_gauss(copy, sy, c, 2);
-		}
-	}
-	return copy;
+	BlurBaseOperation::initExecution();
+	BlurBaseOperation::initMutex();
 }
 
-void FastGaussianBlurOperation::deinitializeTileData(rcti *rect, MemoryBuffer **memoryBuffers, void *data)
+void FastGaussianBlurOperation::deinitExecution() 
 {
-	MemoryBuffer *newData = (MemoryBuffer*)data;
-	delete newData;
+	if (this->iirgaus) {
+		delete this->iirgaus;
+		this->iirgaus = NULL;
+	}
+	BlurBaseOperation::deinitMutex();	
+}
+
+void *FastGaussianBlurOperation::initializeTileData(rcti *rect, MemoryBuffer **memoryBuffers)
+{
+	BLI_mutex_lock(this->getMutex());
+	if (!iirgaus) {
+		MemoryBuffer *newBuf = (MemoryBuffer*)this->inputProgram->initializeTileData(rect, memoryBuffers);
+		MemoryBuffer *copy = newBuf->duplicate();
+		updateSize(memoryBuffers);
+		
+		int c;
+		sx = data->sizex * this->size/2.0f;
+		sy = data->sizey * this->size/2.0f;	
+		
+		if ((sx == sy) && (sx > 0.f)) {
+			for (c=0; c<COM_NUMBER_OF_CHANNELS; ++c)
+				IIR_gauss(copy, sx, c, 3);
+		}
+		else {
+			if (sx > 0.f) {
+				for (c=0; c<COM_NUMBER_OF_CHANNELS; ++c)
+					IIR_gauss(copy, sx, c, 1);
+			}
+			if (sy > 0.f) {
+				for (c=0; c<COM_NUMBER_OF_CHANNELS; ++c)
+					IIR_gauss(copy, sy, c, 2);
+			}
+		}
+		this->iirgaus = copy;
+	}
+	BLI_mutex_unlock(this->getMutex());
+	return iirgaus;
 }
 
 void FastGaussianBlurOperation::IIR_gauss(MemoryBuffer *src, float sigma, int chan, int xy)
diff --git a/source/blender/compositor/operations/COM_FastGaussianBlurOperation.h b/source/blender/compositor/operations/COM_FastGaussianBlurOperation.h
index 6c3e373472b..1f71fe7f9ed 100644
--- a/source/blender/compositor/operations/COM_FastGaussianBlurOperation.h
+++ b/source/blender/compositor/operations/COM_FastGaussianBlurOperation.h
@@ -30,7 +30,7 @@ class FastGaussianBlurOperation: public BlurBaseOperation {
 private:
 	float sx;
 	float sy;
-	bool iirgaus;
+	MemoryBuffer* iirgaus;
 public:
 	FastGaussianBlurOperation();
 	bool determineDependingAreaOfInterest(rcti *input, ReadBufferOperation *readOperation, rcti *output);
@@ -38,7 +38,8 @@ public:
 	
 	static void IIR_gauss(MemoryBuffer *src, float sigma, int channel, int xy);
 	void *initializeTileData(rcti *rect, MemoryBuffer **memoryBuffers);
-	void deinitializeTileData(rcti *rect, MemoryBuffer **memoryBuffers, void *data);
+	void deinitExecution();
+	void initExecution();
 	
 };
 #endif
diff --git a/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp b/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp
index 44b4c26fb64..71fc53e8f8e 100644
--- a/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp
+++ b/source/blender/compositor/operations/COM_ViewerBaseOperation.cpp
@@ -50,8 +50,9 @@ ViewerBaseOperation::ViewerBaseOperation() : NodeOperation()
 
 void ViewerBaseOperation::initExecution()
 {
-	// When initializing the tree during initial load the width and height can be zero.
-	initImage();
+	if (isActiveViewerOutput()) {
+		initImage();
+	}
 }
 
 void ViewerBaseOperation::initImage()
@@ -79,7 +80,6 @@ void ViewerBaseOperation::initImage()
 }
 void ViewerBaseOperation:: updateImage(rcti *rect)
 {
-	/// @todo: introduce new event to update smaller area
 	WM_main_add_notifier(NC_WINDOW|ND_DRAW, NULL);
 }
 
diff --git a/source/blender/compositor/operations/COM_ViewerBaseOperation.h b/source/blender/compositor/operations/COM_ViewerBaseOperation.h
index 58101911550..f5f30809f65 100644
--- a/source/blender/compositor/operations/COM_ViewerBaseOperation.h
+++ b/source/blender/compositor/operations/COM_ViewerBaseOperation.h
@@ -42,7 +42,7 @@ protected:
 	bool doColorPredivide;
 
 public:
-	bool isOutputOperation(bool rendering) const {return true;}
+	bool isOutputOperation(bool rendering) const {return isActiveViewerOutput();}
 	void initExecution();
 	void deinitExecution();
 	void setImage(Image *image) {this->image = image;}