That function is taking on average 10ms per frame for my server with around 30,000 networked objects in it. I did a deep profile of it, and the part that is taking a long time is NetworkServer.UpdateServerObjects. I've looked through the source code for that function, and it seems simple enough. The slowest part of that function should be the call to NetworkIdentity.UNetUpdate, but that is negligible in the profiler. I've attached a screenshot of the profiler for it. Any help on how this...
NetworkIdentity.UNetStaticUpdate slow performance
NetworkIdentity.UNetStaticUpdate slow performance