Could you explain a little more what you mean when you say "the rendering stops"? That shouldn't happen, actually. :-/
Filters are not cheap, performance-wise, because they always require one (or more) additional render steps and require the GPU memory for the render steps.
Have you tried the "cache" method of the filter? That would render the filter only once and then keep the result. When the object changes, you can call "cache" again to refresh it.