Both in 9.10 and 10.04 I experienced poor performance of Netflix running under a virtualized Windows XP in a Dell Inspiron 1420N laptop with Intel videocard.
I tried different options, but nothing seemed to work (RAM, video RAM, 2D and 3D acceleration).
Then I found a post somewhere mentioning that the problem was the infamous Pulse Audio.
So I switched the audio plugin to OSS and… it worked!
Netflix is now snappy, with a few hangs, true, but very watchable. While before there was no moment without dragging, now it is mostly flawless.