External Monitor very slow (about 1fps) with chorome and other sw, cup high
 

Dear all,
I'm working on a Dell Xps13, with ubuntu 16.4
I have 2 external monitor connected, + the builtin monitor

On both my docking station (Dell3100 or I-Tec cardual4kdock) I have this kind of problems:

1. Cpu is always very high
2. Google chrome can work only if I disable HW acceleration (only on the external monitor)
3. Many other sw has a framerate of about 1FPS (only on the external monitor)

Here attached the debug.

How I can adjust it?