Checking for updated drivers and reloading is a good starting point as recommended.
How does the system performance compare with the old one on other applications?
What model Xeon is it? Xeons have been around quite a while and it would not surprise me if a real old one was slower.
Did you use a new HD or completely reformat an old one before loading new OS?
Have you run the standard prime95 and memtest to confirm system stability?
After that you might run the quick and free PC testing tool at PCPitStop to see if it reveals anything.http://www.pcpitstop.com/
If problem continues, please provide a complete list of components for old and new systems, with links to newegg for the new system. There might be some incompatibility issue with components.
You can also get software to benchmark components to try to isolate the problem - could be just one bad component - and almost any component.