Time delay problem!!!

I have a ###ne stealth chipped which works fine. I have backed up a jap version of “Dance Dance Rev 3rd MIX” which is a dancing game involving good timing skills. My friend has this on a non-chipped jap PSX and the game works fine, but on my version as you play there is a delay between music and picture which gradualy increases untill about 1 sec which is very annoying. I have ruled out the possibility of a boot disc fault as I have the same problem using the disc swap method. Is it the chip, and if so, would putting a switch on every wire help?