Vacuum takes more than 1 hr

I have a table with about 30 columns and 200K rows. When I perform a vacuum
on it (no analyze) it takes usually a little more than 1 hour. Since I do it
everyday, for me, this basically means my database, which is now getting
about a million queries a month, is down for an hour every day, since all
selects to that table wait until the vacuum is done. I have smaller tables,
10 columns, 5K rows, which see, to be very quick with vacuum. Any ideas on
how to speed vacuum up?
Thanks,
Rich