have you tried 'SPUSYNC on' into audio menu?
if that still freeze, i suggest one thing:
at ISO loader Press Menu button, then go to system menu and Backup all files
Now open text file /sdcard/fpsebackup/gamelist.ini, copy any block to end of file, and then change License like [SCES_003.45] to the license of your game, to know the license go to www.sonyindex.com
, check the region of your game, and find the license.
into this new Block, change the line Flag0=x to Flag0=20
Restart Fpse, at loader press menu and go to system to 'restore all files'
Press Back to go back to loader, and reload your game.
Tell me if it works.
Flag0=20 add perfect scanline timing for GPU