Hi Sophie
Unfortunately a lot of TS3 players encounter problems when playing the game on their Mac. These can include crashing and freezing, especially when using CAS. A lot of these issues can be avoided or at least improved by the following measures.
Tips for Mac simmers
Firstly, manually reset your RAM while playing. See BluebellFlora's guide on how to do this: http://bluebellflora.com/the-sims-3-on-a-mac/resetting-ram-during-gameplay/
I restart my computer before I play TS3. Close down other things that are running in the background. The memory used as seen in Activity Monitor is at about 3GB after the restart. If I open the Launcher it goes up to around 11 GB (that's all I've done - just opened the Launcher!). At this point I reset the RAM. Then I hit play and get through the opening sequence. I then press cmd-return to put the game in windowed mode from time to time while playing (and always before saving or using CAS). That way I can keep an eye on the memory and reset RAM if necessary. Being in windowed mode also allows you to close the game using force quit if it freezes up - it's better to crash the game than your whole computer.
Second tip is to save frequently. I save at least once per sim day. Use the option to Save or Save As, rather than the combined Save and Quit.
Make sure you are patched up to date. The 1.63 patch included fixes for Mac simmers that did actually improve the stability of the game on our operating systems, so it is well worth updating to at least that level. The current patch is 1.67.
The game runs better if you switch off the memories system and disable the in-game Store and social features.
For general advice, information and tips on how to play TS3 on a Mac, read BluebellFlora's guide here: http://bluebellflora.com/how-to-play-the-sims-3-on-a-mac/
Manual superpatch
Many simmers find that patching their game via the Game Updates tab of the Launcher does not work properly. It is then better to download and apply the manual superpatch. It is important to download the Mac version rather than the PC version, and to pick the right one for your region. Be aware that if you are using a disc you need to choose the correct 'regional' file but if you are using digital download through Origin then you should use the file designated 'region 7'.
Instructions and the links to the downloads can be found in the Mac section of the forums at thesims3.com here:
http://forum.thesims3.com/jforum/posts/list/549552.page
If you use any mods or custom content, be sure to remove them before patching.
Caspin
