Killing the lag monster

Two methods of greatly reducing crashes have been discovered:
Turn on Advanced menu with ctrl-alt-D
Go to debug menu:
Set XferThrottle set to 1500 instead of 15000
Set FSDestroyGLTexturesImmediately set to TRUE
Note that the second option flushes textures 'behind you' every 20 seconds, so can cause texture reloading and some additional lag when turning around. But... is preferable to crashings. : )