How I get the Unity editor to take less time coming back after losing focus?

When I’m working on a client/server app, I have to switch back and forth between the Unity editor - minimizing/maximizing, alt-tabbing, etc. Every time I want to get back intot he Unity editor, it seriously takes 30s to 2min. How can I shorten this time I can alt-tab more freely?

It turns out to be the fact that I had the project on a USB drive. If I copy it to the HD and open it from there, it runs just fine, even if I have Unity/MonoDevelop running from the USB drive.