We are running VirusScan Enterprise 8.5.0.i, Scan Engine 5200-2160. Some of the workstations have been patched to revision 5. Although, many have not been patched at all.
Immediately after the daily dat file update, the process mcupdate.exe spikes the CPU to 100%. PCs which have not been patched to revision 5; the PC becomes unusable for 5-20 minutes. The same PCs after they have been patched to revision 5 behave some what better. The update still spikes the CPU to 100% usage but lasting only about 3-5 minutes. Towards the end of this 3-5 minute spike, the CPU usage will drop some and the PC will be somewhat usable.
Approximately 25% of our PCs are experiencing this high PC utilization. The remainder of the PCs run the update without problem.