On a terminal server, are the values for the following two Firefox user preferences per user or per terminal server?

  • network.http.max-connections-per-server (15 is the default value)
  • network.http.max-persistent-connections-per-server (6 is the default value)

Background: We have a Microsoft Server 2003 R2 Terminal Server Sun X6250 blade with performance issues relating to Firefox and Google Apps email. The blade has 8 cores and 32GB of RAM. We have approximately 30 active users. Everyone uses Google Apps Enterprise Edition web based email. Once or twice a week the server CPU utilization will approach 100%. The Task Manager process list sorted by descending CPU utilization shows almost all firefox.exe processes at the top. Some of the Firefox processes are constantly consuming 5 to 9% of CPU utilization. When the user closes the Google Apps email tab the CPU utilization drops down to 0 and then it consumes an occasional percent or two. We don't see this behavior when using Internet Explorer 7. Most users want to user Firefox rather than IE.

My theory: Google Apps Email is an AJAX application that uses persistent connections. Firefox is looping when Google Apps Email is requesting the seventh persistent connection to the same Google server. Of course this theory is invalid if the user preference network.http.max-persistent-connections-per-server is per user and not as I suspect per terminal server.


Firefox prefs are always per-user, even the modifed version that uses group policy still enforces the setting per-user

Most likely you're hitting some JS bug in firefox, however next time you should check running TCP connections (netstat in a command prompt) and see if you aren't hitting any limits there.


Do your users have Firebug enabled? Google advises disabling it for Gmail.

  • I have Firebug disabled on my Firefox. I have not seen any users with this add-on installed. – PLA May 21 '09 at 18:27

All the JS & AJAX for sure. I'd say having chat enabled as well doesn't help. maybe you can force your users to use the html legacy/compatibility version of gmail & see if the issue goes away

  • When the user uses the "Older version" link the problem goes away. Unfortunately Google Apps Mail will revert back to the latest version after restarting the browser. We also want to use the latest version. There are some useful features in the latest version. – PLA Jun 4 '09 at 13:19

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