Best video format for Infuse on ATV2

Hi, Hopefully a quick and easy answer from someone, have search and can find lots of buffering isse but noone seems to have ask the below question.

I get buffering issues when using the Infuse Player (which I love) streaming over wifi from my windows 7 laptop

These issue seem to happen when using mp4 format 720x1280 on my movies that are 1GB+ files

Can you advise if there is a preferred format / size / video size that would resolve this?