I would probably recommend upgrading your hardware because I get the same issues on my PC, my uncle's PC which is way over the recommended specs for OMSI 2 still lags sometimes but is much more consistent. I don't mean that you have to go and blow 2 grand on a new gaming PC, I would just look at what you can upgrade to. Also I think that OMSI2 rely's on cpu power more than anything else (could be wrong here).