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

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

Thank you.

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.