I play the sims 3 (with several of the expansions installed) on my laptop all the time and it runs fine (mostly) but on my desktop, which is by far more powerful, the sims 3 has problems but only after 30-60 minutes of gameplay. The game slows down and the camera becomes laggy but the FPS does not appear to change and changing the resolution to even its lowest setting has no effect on the lag (I did not want to change any of the graphic options because they required a restart). The tree animation and particles all run butter smooth but the Sims themselves, the camera, and time all lag around and are extremely sluggish and by time I mean the speed of which time is supposed to fast forward when clicking the 2x or 3x buttons is drasticcaly reduced. It has gotten to the point where 2x speed is faster than 3x speed but normal speed is uneffected except for a sluggish camera and choppy animations. Quiting and reloading fix the problem but only for 30-60 minutes and then it returns. Turning on SLI has no effect and I have tried deleting the games 4 chache files but that did not solve anything.
It sounds like a memory leak issue and I have read that installing many expansions actually decreases performance eventually. It seems "eventually" is every 30 - 60 minutes for you.
There isn't much you can really do since it seems to be a design flaw. Try to defrag your hard drive. Maybe installing more RAM may delay the performance issue. But if you already have 8GB of RAM, then I doubt increasing it will make any improvements.
You can probably get better answers by going to the Sims 3 official forum.
I did a defrag, only had 5% fragmentation, and I see no noticable difference. I have 12gb of ram so I do not believe that is the problem. I find it really weird that my laptop does not have this problem yet I run the Sims 3 at the same settings as my desktop with the same expansions. I have been searching the web for a couple of days but I haven not found the answer yet which is why I posted.
You are probably right in that I should check the official forums haha. Thanks for the advice so far!