Hi Nilehorin,
Welcome to the forum. Unfortunately the processor doesn't meet the minimum specs of 2.4 ghz without it using it's turbo boost. Which puts stress on the processor because it has to run at maximum just to reach the minimum requirement for the game.
The Intel HD Graphics chips are known to not work well with Sims 3.
All in all, this computer wasn't meant to play games it's made more office/homework, watching video listening to music and other light tasks. Not so much for gaming.
Sadly there is not much you can do to increase the performance of the game on this system. If the game isn't already on its lowest graphics settings, you can try that, but it may not be much improvement.
MrsFlynn