Thanks Uhrwerk. But come on, would you care to tell me more - where to look for the first 3?
Not sure 100% for 4 (more like 85 ) but
A. lo mem = textures swapping more often
B. VRAM is slower even than system memory, albeit video mem.
C. I guess rendering time increases with texture size.
I'd be happy to be wrong.
I thought of using large transparent sprites to somehow simulate volumetric light (stop laughing). I suck at shaders.