performance of accessing textures


i am measuring a strange performance decrease from 7fps to 4fps just when binding another texture for texture data upload per frame with glTexSubImage2D().

could someone explain to me, why?

before, im generating 2 texture ids, initializing the textures with glTexImage2D().
then every frame, i access the textures to upload data.

when i bind texID[0] i get 7fps,
when i do the same, but bind texID[1] instead, i get 4fps. whats the issue?


Maybe there’s one resident texture but not the other.

how can i affect, that a texture is resident?
i hjave 512mb of texture memory, and all textures can be resident.


But if you could develop more what you encounter just because I’m afraid we misunderstood each other.

If I understood well, you have 7fps for some texture, but when you use the other one (with same size and data), you only have 4 fps. Is that correct ?

its half correct, i use both textures.

just now i am speaking about the update of the texture data per frame.
both textures have the same size and format, so i can updata the same data into each of the textures.
when i just bind texture0, i get 7fps and when i just bind texture1 for the update i get 4fps.