Isle of Dreams stuttering/freezing

[Beetroot Bertie]

Hi. I've been having some issues when playing the Isle of Dreams course, notably it momentarily stuttering (or freezing for longer periods). When playing it offline there's micro-stutters which can be seen by simply rotating the aim camera round continuously. Playing online seemed to exacerbate the issue - when I tried to play the course online with a friend the other night the stutters became more pronounced, more like freezes for a second or three, rendering it unplayable.

The other courses run fine though.

It's hard to tell but based on the figures in the msi afterburner overlay, it looks like there might possibly be CPU spikes in those moments. The CPU and GPU don't seem to be overly taxed normally during the game (i5 4690, GTX 1660 super, 16 GB RAM). Reducing the resolution and/or graphics settings, LOD etc doesn't appear reduce the stuttering either.

I'd be grateful for any suggestions to help alleviate this, or just to see if anyone else has the same issue. For what it's worth, my friend didn't have such issues but he's running a 2080 Super with a newer 10th or 11th gen CPU.

EDIT - 3 Aug 2022:
I've just swapped out my i5 4690 with a recently purchased i7 4790 and it's really helped with the stuttering/freezes on Isle Of Dreams. It's running smooth now, although I've yet to see how it fares when playing online. Maybe the extra hyperthreads have made the difference? I just thought I'd mention it in case anyone has a similar issue, or if it helps pinpoint to anything perhaps CPU bound in the code.