Can I use a single PBO to perform pixel transfer (including render to vertex array) to several different textures of many different sizes and expect maximum PBO speed?
I’m only guessing here, but I can’t see why using one PBO for updating multiple textures should slow things down. Presumably all your textures have the same number of components (alignment!) etc?
In any case it should be easy enough to come up with a test case, and do let us know the results!