Working on images in indexed mode is laggy
Gimp Version: 2.10.12 Windows 10
In my workflow it happens a lot that I index the colors of an image and then export it. Then undo the indexing and continue working. I sometimes to that multiple times within minutes to see the effects of tiny adjustments in my final indexed image. In the previous version I've been using (think it was 2.9, didn't update for a long time) the export never was a problem. Yet now I've noticed that if there are layers on my image then for some reason the export takes ages (about 20 seconds). It works, if I first use "flatten image".
The general performance on indexed images seems to be lacking. It takes for instance a few seconds to paste another image in an indexed file or also just to open an indexed file.
You should be able to reproduce this easily.