Could be my computer?.......I"m getting a lot of "Please Wait" dialog in yellow and Qimage takes forever to respond.....I've already lowered the quality of the thumbnails to minimise processing.
The "Please Wait" yellow reminders are generated when Qimage is building thumbs and cache, and you ask it to do a different chore.
Just let it finish the "build" and no more waiting time.
Look above the thumbs and watch the numbers changing.
Fred