I'm used to the same thing with SageTV. With the Boxee software running in Mac OS, queueing up FWD/REW operations would actually make the video freeze for quite a a while. In fact, unless you were doing anything but one to a few operations (and then not super quickly) it was completely unusable. You could not skip around through 30 minutes using the 30 second skip for instance.

With Sage, I can use the 10 second skip and FWD or REW throughthe entirety of a 2 hour movie without any issue what-so-ever. Or I can use 30 second or 2:30 - I have 10 and 2:30 set on my remote because those are the most useful for TV commercial breaks.