Originally Posted by Mussels
HT helps a large amount with this kind of decoding, assuming he's using a multithreaded decoder. with HT on, my 1.6GHz atom can decode 720p files (~1.1GB size) flawlessly
actually hyperthreading on the old P4's cuased huge performance bottlenecks and it had a high missrate and cuased cache and decoder flushs, the behavior he is describing is very symptomatic of premption cache flushing. disabling HT will resolve this issue if thats the case and the test is very simple.