By way of Rich Turner's blog post:
Many people are concerned about the performance of their Enterprise Services components compared to their old COMPlus implementations. In order to discuss this issue, I (along with a couple of colleagues) wrote a paper published here on MSDN.
The paper essentially highlights the most optimal way to create Enterprise Services components and that if our guidelines are followed then your Enterprise Services components will, by and large, match the performance of COMPlus components!
Comments welcome ;)
I am looking forward to this one as many of my readers know I have spent a great deal of time with EnterpriseServices, doing my own performance testing, stress testing, etc. If you are considering the need for ES, take a look at this paper.