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Description of problem:
Firefox is not responding for tens of seconds when connecting to some sites. I didn't find a reliable pattern, I have just these clues:
  * it may be more frequent when connecting to kerberized sites
  * based on tab header, the hiccup occurs after the name is resolved to IP (favicon stops spinning to left, freeze, page loads)

Version-Release number of selected component (if applicable):
firefox-17.0.6-1.el6_4.x86_64
xulrunner-17.0.6-2.el6_4.x86_64
note: I started noticing this behaviour sometimes since FF 4.0

How reproducible:
no real reproducer, sometimes frequent, mostly not at all

Steps to Reproduce:
1. connect to some site
2.
3.

Actual results:
firefox hangs temporarily for quite a long time. No window can be used.

Expected results:
firefox loads the page instantly

Additional info:
I'll attach bt of $(pidof firefox) process. If you need anything else, please request it.

The main tread waits in krb5_sendto_kdc(), in deep in _nss_dns_gethostbyname4_r() which looks like some resolving problem.

Unfortunately, there isn't any easyfix for that. It needs to move the krb code to another thread and make it async.

This request was not resolved in time for the current release.
Red Hat invites you to ask your support representative to
propose this request, if still desired, for consideration in
the next release of Red Hat Enterprise Linux.

Upstream bug - https://bugzilla.mozilla.org/show_bug.cgi?id=1014061