I'm in the final stages of optimizing my game. I use three different texture sizes depending on how big the screen of the mobile is (big for H>1280, medium for H<=1280, and small for H<=640).
I want to know what's more efficient (FPSwise) for the medium screen size (640 < H <= 1280) a big 1024x1024 PNG texture or 2x512x512 PNG textures.
One texture means one texture change (setup) per render so that's good; but 1024 is big. The two 512 textures mean 2 texture changes per render , but on the other hand they are smaller. Which way is best?
POT textures do not need to be squares. They just need to have the power-of-two dimensions. So, you can use one 1024x512 texture and not need to switch textures during render.