does generally using mipmapped textures improve performance?
Yes because distant objects will use smaller textures automatically.
But do they not occupy the same amount of memory space then...
I would just keep it the same and not suffer the reconversion...
I would just keep it the same and not suffer the reconversion...
PNG's are lossless so the reconversion should not cause any "suffering". Surprisingly you can often make the original conversion from 32bit to 8 bit without losing much too, particularly with textures.