Super slow and high GPU usage

Hi,

My XPS 15 9560 will get very slow sometimes event the mouse pointer moves with lag and slow, most of the time when it happens I can see very high GPU usage which is mostly because of "Desktop Window Manager" and "Client Server Runtime Process" processes. I have tried updating the drivers and installing them but it didn't help, also tried Dell online diagnostics tool but it didn't find anything either.

I am running on latest version of Windows 10. and you below you can find some screen captures of my task manager,

Thanks