We are running hyperv and some of our guest os systems are seeing network latency.The strange part is if you reboot the server it resets itself and over time has the server is used the latency climbs. e.g. on reboot if I ping another server it will show a reply between time of 1-4ms and over time that number will climb to over 1200ms. Some guests have this issue while other's do not. It is not limited to a single host. Some of guest images are new, other are to P2V and some are migrations from VS 2005 R2.
I have tried playing with the offload settings on the host nics and that seemed to just the climb rate.