While I did not find performance to be unbearable, it is inconvenient (W takes 2-3 seconds on my machine, but it’s a very old box).
The quality of the preview is absolutely horrible, useless.
Already processed image with Alt+W sticky preview:
Zoomed in:
Same image in darkroom:
In darkroom, zoomed in:
JPEG preview displayed in Geeqie:
JPEG preview in Geequie, zoomed in:
I then disabled the ‘prefer performance over quality’ setting, and there was a change, but it’s only a blurry image instead of a pixelated one (a different shot, to better show image quality):
Sticky preview at 100%
Darkroom:
JPEG preview in Geeqie, zoomed in:
