XPS 15 lagging

I got a thunderbolt, I got 3 screen, and i see that when i play game, the Nvidia GPU is to 99 % and when it's start lagging the GPU is about 60%, sometime the intel GPU start growing to 80% - 100 %.

My bios, is up to date, my video card is up to date, everything is to the latest version. I run scan, stress tools, bios update etc ... i try to play to Escape From Tarkov. I run the Nvidia Experience, set the graphic Nvidia by default for 3d, but it's seen to always get a fight between intel integrated card and the nvidia.

I update my video card driver, reduce my graphic nothing solve the problem.

The problem seen to be random! Sometime everything going well, and other time lagging enought that the game is unplayable.

When it's lagging a lot, and i quit the game, my pc continue to lagging 5 minutes after.

I got a XPS 15 with 32 G of ram and SSD drive.

Everything is ok on the side of the hardware.

What's going wrong ?