[ubuntu] 16.04 on NUC5I5RYH : video & sound problems

I've updated my Intel NUC from 15.10 to 16.04 and I've get some sound and video issues
sometimes sound is craqueling, noisy or ruing in slow motion
video playbac on web browser is sometimes slow too
I don't know how to fix that
My nuc is coected to LCD screen through HDMI for video & sound
another point related point:
in the Software & Updates App, Supplementary drivers tab, I have 2 entries:
1: Intel corporation: Broadwell-U Audio controller:
==> should I use HDA driver DKMS or not?

2: Unknow peripheral:
==> should I use Processor microcode firmware for intel CPU or not?