High memory limit setting (even if not filled) slows down GIMP
thank you for creating and maintaining GIMP, and maybe following info is helpful to improve it:
GIMP version: 2.10.18
Operating System: Debian (Sid)
- An image, about 1000x1000 px but more than 500 layers of it, tthe majority of layers usually set to invisble (with the eye symbol)
- After loading the image, the status bar says 2.9GB memory, the performance dock 8with the diagrams etc.) says 1.4GB cached
- In the settings, the memory limit is 4GB (and up to 8 threads, but changing this to eg. 1 doesn't change following behaviour)
Example scenario 1 (good):
- Setting some layer to visible/invisible with the eye symbol.
- Works without delay
Example scenario 2 (bad):
- Changing the memory limit from 4GB to 30GB (there's enough RAM for that, and note that the image still uses less than 4GB)
- Then again setting some layer to visible/invisible with the eye symbol.
- The layer content appears/disappears much slower, it can be seen how the image is redrawn in multiple parts.
- Notable higher CPU load than before during that operation.
- This affects many other operations too, eg. closing the iamge and loading it again takes 3-4 times longer with 30GB than 4GB.
- Setting the memory limit back to 4GB makes it fast again.
Profiler file: Is appended.
Note I have 4 markers in it: The good section is between aaa1 and aaa2, and the bad section between aaa3 and aaa4 gimp-performance.log