Severe DNS Problems, 6.2-RELEASE, BIND 9.5.2

[george+freebsd at m5p.com]

I'm having severe DNS problems.  I'm running 6.2-RELEASE, and I upgraded
to the bind9 port (after cvsup) on July 14.  Starting yesterday morning,
DNS became very, very slow.  If I repeated a "dig" command three or four
times, I could get an answer after 20-30 seconds.  This morning I cvsupped
again and installed the bind95 port.  Still very, very slow.  I will
probably shift my server to a FreeBSD 7.0 system this weekend, but I
would like very much to understand what's going on.
-- George Mitchell