PocketMatrix

Depending on what you do in order to create the sprites and hold them in memory I really do not think it really matters.

I have always created seperate files for the sprites, mainly since I have animated sprites and it is easier to implement with seperate files.

I suppose it is a subjective opinion but I would choose single files over one big one each time.

Based on the processor cache, several smaller sprites or vertically stacked sprites are likely to be faster.

Good blog post here: