Re: Spawning new session leads to crash
This workaround took days to isolate. I hope this helps someone else.
Debian sid AMD64 8800GT.
InitialPixmapPlacement must be 0 or 1. Leave it at 1. 2 or 4 leads to VT crashing occasionally when switching VT. IIRC message was something about EVO DMA exhausted. GlyphCache=1 appears to be safe and gives me a 3x performance improvement in gnome-terminal (still about two to four times slower than the integrated Intel graphics in my low-end laptop).
In addition, DFP-0 Flat Panel Scaling Force Full GPU Scaling must be DISABLED. I also set the GPU Scaling Method to Centered. Display will go momentarily black when making this change.
With these two changes loaded when opening a new session I can switch VTs without X crashing. Otherwise it is a lottery when pressing CTRL-ALT-F7/F8. X may crash (VT becomes a black terminal with an underscore flashing) and the keyboard locks up. It is usually possible to ssh into the box and chvt may or may not work to gain access to the remaining VT. Reboot usually necessary.
Good luck everyone! Please don't expect a reply whether this workaround works for you or not. I've seriously considered cutting my losses and purchasing an AMD/ATI card just so I can get some work done.