ATV2 : Non-smooth playback in general and buffering on larger files

Hello everyone,

Thanks for your help on my previous topic, now new problems have emerged.

From Mac via SMB(SMBup):
+Excellent video/sound quality, no subtitle issues
-Buffering issues with files larger than 5GB normally
-Playback is not constantly perfectly smooth. Some periods it is, some sequences are a bit choppy(dropped frames?).
-Files pause randomly for buffering (i.eg. after 30 minutes) and if I press play button twice it keeps playing. It seems like the connection gets killed sometimes?

From Mac via AFP (I don't use this!):
+Excellent video/sound quality
-Buffering issues with files larger than 5GB normally, subtitle issues, playback is not constantly perfectly smooth. Some periods it is, some sequences are a bit choppy(dropped frames?).

NFS does not work whatsoever on my Mac.

ICEFILMS:
+ Excellent video/sound quality, no buffering issues, no subtitle issues
- Playback is not constantly perfectly smooth. Some periods it is, some sequences are a bit choppy(dropped frames?).

Setup:
ATV2 connected via HDMI to Sony Bravia TV
Optical sound is connected to the TV - Sound is sent through HDMI on the ATV
Both ATV and MacBook Pro(late 2008) is connected to my router via wireless (g, not n)
Running the latest stable XBMC, not nightly or monthly or anything.


Any solutions for the smoothness? Also anyone that has some ideas for the random pausing over SMB? The buffering issue with big files is not an important problem, I think this is just due to the files being too big for my network to handle.