3.1 introduced a new setting called
textureCacheSize.
What this does from what I can tell is cache in memory textures when they are not in use for quick loading.
By default this is set at 32megs and is not bad for mid/low end systems.
However for multibox or highend systems this might have some draw backs.
Grab your multipass and lets continue.
textureCacheSize is set by default at 33554432 bytes (32megs).
Higher end systems can set this... well higher.
Multibox or lowend systems can do the same but by setting it lower depending on your system's ram.
In my case I quadrupled the value to 134217728 (128megs) of texture cache.
This is quite easy to do in game by typing: /console textureCacheSize followed by the size of the texture cache in bytes.
Examples,
128 megs: /console textureCacheSize 134217728
64 megs: /console textureCacheSize 67108864
32 megs (Default): /console textureCacheSize 33554432
16 megs (Multibox/Low End): /console textureCacheSize 16777216
8 megs (Low End Multibox): /console textureCacheSize 8388608
Be sure to restart WoW after you set the values.
Just some basic examples, as of right now I'm 100% unsure how high this goes or what the cap is but I've been fiddling around with it ingame.