Weird game optimization (Call of Duty: Modern Warfare 2 (2022))

Why does this game have such strange optimization and how can it be fixed? I played at 70-90 fps, but I constantly had lags and stutters. I tried different settings but nothing helped. The only setting I haven't touched is the amount of video memory allocated to the game. I thought that the more I set, the better the game will work, but lowering the value from 90% to 80%, I lost lags and stutters. Now the same 70-90 fps were very smooth. I realized that before that the video memory was hitting a cut-off and because of this everything was lagging. But I noticed that the game uses about 7 gigabytes of video memory, although the settings indicate that no more than 5. I set the memory consumption from 80% to 60% and nothing has changed. I still have the same 70-90 fps, but with a video memory consumption of 5.5 gigabytes. And I have a question. If I have free resources (the video card is 70%-80% loaded, the processor is 50% loaded, there is also enough RAM), then why doesn't the game use them? Why can't the game give out more than 90 fps if I still have a large amount of resources.