If the game still lags after the update, try clearing the game's cache through the PS3 system settings.
It helps prevent the game from crashing to the PS3 XMB menu. Finding the Correct The Sims 3 PS3 Update (.pkg) the sims ps3 pkg upd
If you are installing a digital PSN version of The Sims 3 as a PKG, you will also need the corresponding .rap file. This acts as the digital license key to unlock the game and prevent "Renew License" errors. Prerequisites for Installation If the game still lags after the update,
Before updating, ensure you have a backup of your save data. 256 MB RAM
A controlled test on a CECH-2001A (PS3 Slim, 256 MB RAM, 256 MB VRAM) shows: