This tool is intended for players, which will clean unnecessary things in the save files. Don't be afraid because it has been used by more than one thousand people. However, I still strong recommend that you need to backup your save .
I have collected enough information that it will shrink the save around 30% off, and well boost your save loading. The time shortened is not clear because it will depends your PC.
How to use it.
Choose your save file (it will be in My Documents\ Electronic Arts\The Sims3 (or other similar folder)->Click "Start Clean"->Be sure you have your save back up and then click yes->Done!
How it works:
It will delete all the SNAP TS3 created for each sim in the game. However, the game itself will not delete these images even though they are no longer in use and that's part of reason why the save is so big. Don't be panic! When you play the game, TS3 will re-generate all the SNAP.
Read more and download at Simlogical