Are you using ImageToArray and ArrayToImage? Then could you try to replace Image Display by Intensity graph to display your image.
Are you displaying 60 images per second through Image Control property node? User will be not able to see 60 fps any way. 20fps is for user enough. And property node is updating GUI everytime and is slow.
Could you create code without AF which use similar queues mechanism and generate same memory leak? Then you should share this code with Vision group in the forum.