WCF has lots of limits imposed on it to protect against DoS attacks and other developer brainlessness. What are these limits? And how can they be overriden?

Specifically, if I was to try to send a large number of messages in a short period of time to a variety of different clients, what are the internal WCF limits they may cause messages to be sent slowly.

PS: this question is a much shorter version of my previous question that did not get much attention.

EDIT I have answered the original question. The issue being my async calls were being turned into synchronous ones.