After launching the game I play on perfect 60 fps for a few minutes. After that game suddenly decides to not go over 20 fps and I really have no clue why would that happen since I have a solid gaming laptop which can run Witcher 3 on high settings no problem. Like I said it plays really smooth for the first few minutes after launch then suddenly bam, not playable, stuck at 19-20 frames. Never had that happen on any other game. Tried everything; disabled VSync, hair works off, giving it a high priority for CPU usage, updated drivers.. still nothing. I would appreciate any help!

Check temperatures. High ones, especially in laptops, causes throttle issues, which lead to underclocking.

temps seem fine. Checked all of it. CPU and GPU usage are both low for some reason tho.

Hi, guys! Help me get a copy of the Witcher 3 game. I will be very grateful to you!
If you send it by email I will be very grateful to you
ipad.home.alex@gmail.com

Tried to reinstall it, tought it worked but after 10 minutes of gameplay, again stuck on 20 fps. CPU utilization is only on 30%

Your attachment shows drastical drop if that happened ingame. Something limits its either power or clock rates or anything related to keep it cool.
Also I noticed that you're using only 1 active core at the time. Open Task Manager, go to details of the witcher process after right-clicking on it, right click again on highlighted process and select "Set affinity" and see if all checkboxes are marked. If they are means the problem is not here, otherwise mark them.

Post here your laptop's brand and model name, I will try to look into it.