Issues with Ubuntu 16.04.2 with kernel 4.8

[fotografo]

jerrinot's method worked for me! For anyone confused, my xorg.conf file in /usr/share/doc/xserver-xorg-video-intel-hwe-16.04/xorg.conf looks exactly the same as giuliocoluccia's. I did not edit that. I navigated to /etc/X11/ and ran the command "sudo gedit xorg.conf" to create a new file and then copied and pasted jerrinot's file (this file ) and saved it. Restarted my computer and now there is no more lag on either of my two monitors. I had to go to System Settings > Displays and fix some issues cause for some reason it had my built-in display inside the HDMI monitor and the Display Port monitor was turned off.

HOWEVER, sometimes Chrome does some strange flashing. It's not often but it is happening. But no lag, scrolling is super smooth, no problems other than the occasional flashes.

My setup: Ubuntu 16.04.2 on a Dell XPS 9350 using a StarTech USB3DOCKHDPC. I have one monitor connected to my USB-C port via HDMI, and one monitor connected to the docking station via Display Port. I could try the HDMI cable in the docking station, too...but I'm kind of scared to after spending so much time trying to get my dual-monitor setup working. XD

UPDATE: Finally plugged in both Display Port and HDMI to docking station. Both monitors working fine. Ocassional flashing still there though. My PC is getting hot now and the fan is pretty loud.