Mavericks is slow after logging in

When I start up my Mac Mini, or wake it from sleep, Mavericks gives me the "beach ball" and hangs for about 5 to 10 minutes during that time I cannot open any programs or files. Applications (like Safari) will bounce in the dock, but then stop. Eventually the OS springs back to life and everything goes back to w just fine — like nothing happened. I have already repaired disk permissions and removed startup items, but that did not help.