Here are few things I would recommend you try:
1. Delete your Internet browser cache, cookies and history on your ps3. (This can slow your system down if not deleted after awhile). Here is a video that demonstrates it :
2. Rebuild the system database.(This has improved my frame rate and I haven't froze since. I recommend doing this after every large game patch or after downloading and installing games from the psn store). Here's a video:
3. Also try "restore file system" while in recovery mode.
