Sims 3 jumpy for unknown reason.

I am running the Sims 3 from it's physical CD on Windows 7 64-bit Release Candidate, with a Radeon HD 4870.
Using Fraps, it reports that on maximum settings, I get around 240 fps, dipping sometimes to the mid/low 100s. Though, when scrolling the view around, the game will randomly get quite jumpy. The FPS do not take a hit during this though, and animations seem to be ok, for some reason the camera just acts like the computer is getting overloaded.
Anyone have any suggestions?

Try screaming at your PC like John Travolta and it might stop jumping. You can always tie it down or pull out your gun if worst comes to worst.

Increase RAM, defrag, etc.

Sorry for lack of specs. I am using 4GB of OCZ Fatal1ty ram in dual channel, clocked at 960mhz (oc'd processor so that's the closest I can get.) I think it may be my hard drive, just a Seagate 7500rpm, because Oblivion is also quite twitchy in the same way, so perhaps it's loading the textures slower than the card is rendering them? I'm not too experienced with all that yet.