After upgrading to:
testing/xf86-video-intel 1:2.99.917+651+g34f63f2-1
testing/linux 4.6-1

In combination with my existing Xorg option:

cat /etc/X11/xorg.conf.d/20-intel.conf
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "TearFree" "true"
EndSection

The screen starts to flicker after Xorg is started when moving the mouse. As Window Manager I am using XFCE. Additionally dmesg shows:

[ 853.479397] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* pipe A underrun
[ 853.479420] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
[ 884.983087] [drm:intel_psr_work [i915]] *ERROR* Timed out waiting for PSR Idle for re-enable

where the Time out line repeats.

Disabling TearFree solves removes the Flicker.