This topic was discussed a little bit here
http://forum.ppcgeeks.com/showthread...ht=youtube+lag
It seems like this problem is fairly common. Even with me. Im not sure what causes it, when I experienced it I was on low battery so I am charging now and I have a feeling it will get better on a full charge.
I have plans to flash anyways, so if this doesnt work, it is just another reason for me to do so.