The performance numbers in the multiplex documentation are for a pair of virtual sockets running on localhost, and they represent the ratio of the time taken to transfer N bytes by virtual sockets compared to the time taken to transfer N bytes by real sockets. They're intented to give some idea of the penalty paid for multiplexing. Note that they're not based on the newest version of the multiplex system, and performance is improving.
On the other hand, if you're interested in a multiplexed Remoting transport, then a comparison of the multiplex invoker to the socket invoker is more relevant, and the performance of the muliplex invoker is increasingly respectable. Earlier today I ran a test with 10 client threads making invocations on a server, and the multiplex invoker version took about 2.5 times as long as the socket invoker version. I expect the gap will continue to close.
Ok thx Ron-
Let's see what performance figures we get in the perf lab then if it proves to be an issue we can address it then.