Reshade 4.9.1 with Flatout Ultimate Carnage - moments of stutering.

So I've got quite a powerful PC with nvidia RTX 2060 AMD ryzen 9 and 32 GB Ram.
And Flatout is quite an old game.
But when I added some effects like:
HDR
GloomAO
Tracking Rays
Liquid Lens
Vibrance

The game started to behave starnge. It genereally runs smoothly but now and then it falls into stuttering. The number of frames drops to like 1-2 per sec and then after a while it comes back to a fluent performance.
I tried to inspect which effect is causing this so I turned off each of them one by one. but the stuttering remained in all the cases.
So, what may be the problem and how to get rid of it?

Here is what is turned on:

https://ibb.co/BqRM0Jb

So even setting just the most basic effects like:
MXAO
Vibrance
HDR

result in stuttering desribed above. So there is evidently something in the mechanics of the reshade.
Anyone suspects what may it be?

Anyone confirms these probles?

Frankly it just sounds like you have vertical sync enabled and the extra load on the system from the shaders is causing the game to occasionally shift between two V-Sync "snap points". Try turning it off and see if you still have a problem.

If screen tearing becomes an issue, try using RivaTuner Stats Server (included with MSI afterburner) to limit the framerate, using either "back edge sync" or "front edge sync".

No there is no vsync option.
What's strange I've copied the game folder to my stationary pc. Which has worse graphic card. And everything played smoothly.