texture unit performance question

Say I’m working on a graphics card that has a 4 texture units in hardware but supports up to 8 bound textures at a time (probably through loopback).

If I bind textures on units 1 and 6 only, will this cause a loopback and resulting performance decrease? I guess what I’m asking is if it notices that there are only 2 textures in use or is it the slots they’re in that matters?

usually yes, but in some cases no. this depends on the hardware-design of the 3d-chipset and can’t be answered for all 3d-cards.

I was afraid that would be the answer