If your VMM implementation has over 150 hosts, we strongly recommended that you enable server-optimized garbage collector (GC) on the VMM server instead of the default workstation garbage collector. This can significantly reduce the CPU utilization on the VMM server and improve your performance for parallel VMM operations.
To accomplish this, simply create a new filed named vmmservice.exe.config and place this file in the same location as vmmservice.exe (VMMservice.exe is located in the bin directory of the VMM server role installation)
This file should have in it the following information (bold and indented). If you want to know more about this option, read this link: http://go.microsoft.com/fwlink/?LinkId=102219