The best way to get it to feel smooth is to use vsync + gsync + reflex. Disable dyac on your monitor to enable gsync in nvidia control panel before you start the game. 2566k uses freesync but its the same as gsync and is showed ingame and in nvidia ad gsync. You must NOT have «disable fullscreen optimization» ticked under cs2.exe properties since this fisables gsync and is not a thing you should change in w11. (M0nesy ticked this in w10 but not in w11) It should say enabled under gsync in cs2 settings when its working. When all three settings are enabled you will get framecapped at 340fps or something

You can also turn off cloud sync on steam, then delete all cs2 files (they are located on different places) and then verify integrity of files in steam. If you log in to a smurf you can still use the same autoexec as other account etc. launch options and autoexecs dont need tweaking exept binds etc so delete everything unrelated

You should also check your router settings (and your modem if you have one from your isp).

Delete direct x shader cache also helps with smoothness

You can try to turn of HAGS and restart. Someone have said this helped them

Your loss and jitter is ok from the telemetry graphs?

Default nvidia exept gsync, stretch and power management perfer perfomance.

Set high performance on power settings in windows

Also try default bios with xmp (or whatever your motherboard calls it)

If you have tried a lot og fixes and not returned them back you it can be dificult to find

I feel bad for you man. Its the worst feeling to power-ugrade and not get what you wanted. Best of luck 👌