Other question that comes to mind is if this is with all images or just very large images. Some of the memory intensive tools like blur can take a while to process on larger images, giving the impression that something has hung.
1st October 09:17
All of the ones that change the actual pixels, like burn, dodge, blur, sponge, sharpen, and smudge can give some delay in processing on larger images. Can't speak to the DreamyFX plug-in.