High ping response DC's

Hi there,

I have 2 domaincontrollers in our network, for a kopple of months now these DC's have very high ping response times, only a part of the day.
Strange thing is when is remove my Symantec Endpoint Protection client the high ping response times are gone.

Im running version 11.0.7200.1147 but also have this problem when i use 12.1.
Any idea how to fix this issue?

Regards,

LEVD