Slow animated .gifs

Not sure if this is the right board, but I just got a G5 and it runs superfast until .gifs come along. This is mostly to fix my problem when viewing www.ytmnd.com pages when the sound needs to synch with the .gif. What happens is the sound plays normally, but the first time the .gif plays, it goes slowly, but after it's done loading, it plays at the correct speed.

Just wondering if I need to change some preferences or get new hardware or something. Thanks for any help!