Dell VRTX M520 performance issues

We have 3 Windows server 2012 R2 Core servers in a Hyper-V cluster.  The problem we are facing is a slow degradation in ping response to hosts and guests within this cluster over time.  A reboot of the hosts fixes the issue but cannot be the solution obviously, as it is in production.  These hosts sit in a DELL VRTX chassis and we have made sure the DELL firmware and Microsoft Windows Updates and hotfixes have all been applied. 

We have checked NIC Teaming, disabled/uninstalled AV, made sure no backups are running at the time of bad response times from PING. Response times should be 1ms or less and we are getting 43ms+ interspersed by 1ms fro example. We are not getting request time out anymore but still latency which effects the guests running apps on the hosts.

Dell hardware has been checked and the switch on this chassis has also been replaced.

Anyone experienced anything like this?