I've recently been installing a lot of MS Server products into a lab. One thing I noticed is immediately after the install the server is nearly useless, especially if its a Virtual Server with only one core.
The reason for me was after the install the dot.net framework was busy in the background pre-compiling all the binaries. You can see this be the process "mscorsvw.exe" hogging 100% of CPU time.
According to this blog article http://blogs.msdn.com/davidnotario/archive/2005/04/27/412838.aspx
the pre-compiling is just Temporary and will finish eventually, but, it can be pretty annoying if you are trying to do the configuration immediately after install, or demoing to someone and want a smooth ride.
So, you can manually force the pre-compile with this nice command to flush the queued compiles, go away and get a cup of tea/lunch and hey presto nice performance.
I think I'll include this as part of all build plans of dot.net server based products when installed on Virtual Platforms.