Game suddenly becomes laggy after a few minutes.

Hello, I wrote this on the beamng Reddit page the other day but nothing came up so I thought I’d try here.
“Earlier BeamNG was working fine for me until it suddenly decided to become laggy. I had a look at my CPU, memory, disk and GPU usage and they all seemed normal except the GPU usage which was nearly running at 100%. I updated my drivers and rebooted my pc and the issue doesn't exist until around 2 minutes of driving. I've cleared the cache (standard cache clearing) and ran the game under safe mode yet it still persists. I was wondering what could be causing this issue and if there's any possible fix?”
I’ve now found out that it’s meant to be 100% gpu and I’ve done deep cache clearing but it still happens. I’ve noticed the wait for gpu is averaging around 50ms or more (I don’t know what it was before). I’ve even tried lowering the graphics settings and running it under Vulcan (both Beamng Vulcan and dxvk).
Does anybody know what could be causing this and how I could fix this issue?