Jumpy playback on PS3 but not iPad

When playing "some" media to my PS3 via Wireless, the playback is choppy like it can't buffer it (or its transcoding)
The files are AVI's and it stated the media was compatible with PS3 without the need to transcode - if i put it on a USB and play it on the PS3 it works fine.
However if i run xmbc on my iPad (wireless) it plays smoothly with no jumps etc. Switch back to the PS3 just to check and its still jumpy and stuttering.
I can't figure out what whether its the Network, Media or PS3. This has happened several times now
The files are AVI's and it stated the media was compatible with PS3 without the need to transcode - if i put it on a USB and play it on the PS3 it works fine.
However if i run xmbc on my iPad (wireless) it plays smoothly with no jumps etc. Switch back to the PS3 just to check and its still jumpy and stuttering.
I can't figure out what whether its the Network, Media or PS3. This has happened several times now