GTA:Vice City- glitching in gameplay

[patch god]

Ok, backed up vice city onto a TDK dvd-r at 1x with nero. when i play the game it goes smoothly all the time but i was doing this mission today where you steal a speed boat and when i was cruising with it the game glitched constantly. it was like after every 1-2 seconds for a about a quarter of a second. it kept happening untill i got off the boat. my question is, does this happen to anyone else on the same mission??

edit: there were no disk error messgaes either.