Which broswer are you using?  Under certain conditions, both browsers seem to pause for inexplicable reasons.
Both IE and Netscape will pause for quite a bit, mainly when you have a very large history.  Happened to me quite often, since I kept the history for 999 days (don't ask why).  Clearing the history will stop the pause.  Clearing the caches will also help.
If you have IE5 under Win2K, and access a very slow FTP site, sometimes it keeps trying to access that site when it is listed under My Network Places.  IE will pause for quite a bit before it goes anywhere.  Delete the FTP from Network Places to return to normal.
Hope that might help.