Your 2.9 not doing it gives me a glimmer of hope for 2.10 might not do it either, but my luck being what it is...*sigh*

ek22, I was able to extrude to 200 layers on a Pentium 1gz with 512MB of RAM, running Fedora 14 & GIMP 2.6.11, with no problem, so that really points to there being an issue with GIMP 2.8.x. Either that or there is a problem with GIMP 2.8, only on my Fedora 19 machine, which I doubt.

I can run yet another test, this time with GIMP 2.8.x on Fedora 18, which should confirm one way or the other.

Appreciate it. Just knowing something other than 'sorry mate, your comp sucks' would be better than what I've been getting on the subject so far.

I just had a chance to boot into Fedora 18 and test GIMP 2.8.10. To my surprise, I had no memory issues or crashes in Fedora 18. In my first test, I extruded to a depth of 500 layers, with no problem. I didn't bother testing any further. Obviously, there is some kind of corruption in my Fedora 19 installation and the crashes I'm experiencing in GIMP are not inherent to GIMP 2.8.x.

I had been noticing quite a few random crashes in Firefox, over the last few weeks, but I didn't think much of it, until now. I suspect whatever corruption problem I have in F19 is causing Firefox to crash, as well.

ek22, sorry that I couldn't duplicate and confirm the problem you're having with GIMP 2.8. You might occasionally be hitting a 2.8.x bug with your large images.

A big thanks to everyone who offered suggestions to help me figure this out. I'm glad it wasn't a GIMP problem, after all. I can reload a corrupt Fedora installation easy enough. Shoot, it was time to move to Fedora 20 anyway.

I'm marking this topic as solved.