I want to get an iMac but I want it to be able to play games like the sims 2 and sims 3. If I install the game will it slow the computer down?

If the iMacs is less than 2 years old it will be able to handle those older games without any problem. The computer will only slow down if you are trying to run the game and multi task or if you already have your hard drive installed with a lot of software. If its older than 2 years you might want to see what kind of processor, ram, and video card you have and see if they match the system requirements posted on the game box.

it's may b slow your computer

Not really