Did you remember to tweak the .ini after reinstalling?

zTexCacheOutTimeMSec=5120000
zTexCacheSizeMaxBytes=512000000
zSndCacheOutTimeMSec=10000
zSndCacheSizeMaxBytes=20000000

That's what i use.

I dont think there's a invisibility cheat. There's supposed to be a "invisible" console command but it doesnt work for me, maybe it's been removed in the later revisions of the .exe.