It may not be causing you a problem, but it has caused this problem for me, and apparently many other people on this board. Just read the various posts about new found download speed issues and stuttering on streamed content. Many different descriptions of symptoms of a major network slowdown. You yourself have called out network speed as an explanation for why people are having these problems. Why are all these home networks suddenly so slow. I never had issues with streaming to my ATV even on prior versions of my network using the previous, slower 802 standard.
I worked around the issue by tying my ATV into my network via ethernet, using a spare airport express unit. There is nothing wrong with my network. Just a problem with the wireless link on my ATV, that manifest itself after the update. It's a great product, but something has gone wrong with the update, at least for some of us.
When an item is purchased it will begin to download, at which point the tv will calculate how much will need to be download before you can begin playing it without catching up to the part that is still being downloaded.
The tv is generally quite good at this but if your download speed changes during the download the playback may catch up with the download and cause the pauses you have noted.
If this is a persistent issue you may need to wait a little longer before you begin to watch your downloads or contact your ISP to ask why your download speeds fluctuate.
