After doing some testing to see if I can reduce the stuttering/hitching/frame skipping during racing, I have come to the conclusion that closing down MSI Afterburner along with the Rivatuner OSD software it comes with results in a good percentage of reduction of these small stutters I was getting before.
Whilst it has made a massive improvement to the game, there are still frequent stutters which almost feel like frame skips/short freezes at different parts of races. I am going to send a new report mentioning this. I know shutting down these things was advised but the fact that stutters are still present shows that some work is needed to improve smoothness during races.
I decided not to refund the game as I have hope Turn 10 will fix this. I was quite brazen before about Turn 10 and the devs, but after playing Forza Horizon 3 I was reminded it can be done.