I've been working on a painting in GIMP 2.4 for the last week in my evenings, mainly just to keep my painting skills from atrophy.
I hope to post the finished work soon.
Anyway, the canvas is 3000x2000 pixels, and by the time I reached 70 layers, the file was practically unusable. What struck me odd was that the .xcf file was only 15MB on my HDD, yet when open in GIMP the file was requiring nearly 2GB of memory and scratch disk space.
My problem was I had way too many layers containing only a small area of visible pixels. All the surrounding empty pixels take up memory too, which coming from Photoshop was a complete surprise to me.
The solution was simple, just use the "Layer : Autocrop" command and all the empty pixels are cropped away, leaving the layer sized to contain the visible pixels. If later I need that layer to be either extended or full size, I can just expand the layer to work, then autocrop it again when done.
In my artwork, 70 layers @ 3000x2000 pixels was reduced from 1.8 GB of memory usage (and being sluggish as heck) to just 270MB of memory use and very light and easy to work in.
Others may have known this, but it was a shocker to me.
Linear Mode
