Textures usually reside entirely in fast GPU accessible memory, but cache misses during sampling can still be a problem (so entirely random access across the wh

Textures usually reside entirely in fast GPU accessible memory, but cache misses during sampling can still be a problem (so entirely random access across the whole texture is still worse then accessing nearby pixels). The texture data is 'scrambled' in memory for better 2D spatial locality though, so once in cache, access of pixel groups which are close together both horizontally or vertically is fast. (disclaimer: I'm not a hardware guy, and I also don't know if this applies to all pixel formats and different GPU architectures - texture cache details are also notoriously bad documented by GPU vendors).