Whats better? 4 256x256 textures or 1 512x512 texture?

Can you tell me which way its better? Can you tell me why?

Thank you.

[haust]

Usually, the less you have to change texture while rendering your scene the better it is....
So one 512x512 texture is the best choice. Unfortunatly some "old" cards (voodoo2/banshee/....) don't support 512x512 texture but 256x256 max !!
If you want to target as many cards as you can then you should keep 4 252x252 for convenience.

Bref : 1 512x512 for speed issue, 4 256x256 for "old" cards support issue.