Wow!!!
Congrat, You've discovered a bug!
The rotating tool become insanely huge after 7 to 8 confirmed rotation (confirmed = when you click OK), never saw that (because I never rotate more than just few times)
As a matter of fact the grid, increase proportionally after each confirmed rotation
the rotating grig after 10 or 11 rotations from minus 12 000 pixels to plus 15 000 pixels
Tests made with a Layer + its Mask
A quick work around (I did tried it and it works):
Time to time after few confirmed rotations, just go to Menu > Layer > Layer to image size, and the rotating tool will reset its size, thus freeing memory or process and GIMP get back to its normal speed
BUT you will loose everything outside the canvas
Congrat, You've discovered a bug!
The rotating tool become insanely huge after 7 to 8 confirmed rotation (confirmed = when you click OK), never saw that (because I never rotate more than just few times)
As a matter of fact the grid, increase proportionally after each confirmed rotation
the rotating grig after 10 or 11 rotations from minus 12 000 pixels to plus 15 000 pixels
Tests made with a Layer + its Mask
A quick work around (I did tried it and it works):
Time to time after few confirmed rotations, just go to Menu > Layer > Layer to image size, and the rotating tool will reset its size, thus freeing memory or process and GIMP get back to its normal speed
BUT you will loose everything outside the canvas