If you are using Windows Server 2008 or earlier, and you have a large number of cameras streaming in multicast, you can improve your system performance by assigning a different multicast port number to each camera on your system.
Windows Server 2008 and earlier uses a lot of CPU to process multicast packets when they are on the same port. By default, the system only increments the multicast address assigned to every video encoder it discovers, not the port numbers. You should also change the port number if you frequently use multicast. For example, if you use Auxiliary Archivers or if everything is recorded in multicast.
To change the multicast port of a video encoder: