[Xymon] http tests failing some of the time

I have some http tests that are green most of the time but randomly, typically less than 5 minutes elapse, before they timeout. I have tried all sorts of things to no avail. The http test when green should take no more than a second or two to return but is instead taking 9-14 seconds.

1. -no-ares option
2. xymonnet --debug option, I see where it times out in the debug output but it isn't helpful
3. changed dns server order in /etc/resolv.conf
4. installed nscd
5. changed https to https3, although some of the tests are http and some are https
6. added the ip to the http line in hosts.cfg
7. the http test for the xymon server itself timesout but other remote sites are always green
8. added --concurrency=50 and 100, no help

Works perfectly on a xymon server running RedHat 5.9 32-bit but times out for a small fraction of the http hosts on RHEL 6.4 64-bit. Very odd. Any clues, tips and troubleshooting welcome. Thanks in advance.

~David