I SAID MARK, NOT DREAMORA!
Wrong!
While it may be true that one needs to worry about GPU bandwidth, that is not what is causing the results we're seeing. Copying one texture shouldn't cause an instant drop from 1000fps to 80, when copying 50 only drops the framerate by maybe another 2fps.
This is why I asked Mark to explain it. I'm pretty sure nobody here knows enough about how the cards work at a low enough level to explain why this is happening, and suggest a possible solution.
with low texture sizes, the GPU bandwidth doesn't become a bottleneck so you can do it in "realtime".
Wrong!
While it may be true that one needs to worry about GPU bandwidth, that is not what is causing the results we're seeing. Copying one texture shouldn't cause an instant drop from 1000fps to 80, when copying 50 only drops the framerate by maybe another 2fps.
This is why I asked Mark to explain it. I'm pretty sure nobody here knows enough about how the cards work at a low enough level to explain why this is happening, and suggest a possible solution.