Selen stuck in Firefox

Question

It seems like using firefox 45+ in Selenium from time to time due to loading from https://aus5.mozilla.org/update/3/GMP/45.4.0/20160905130425/Linux_x86_64-gcc3/en-US/esr/Linux % 204.4.0-34-generic% 20 (GTK% 203.18.9% 2Clibpulse% 208.0.0) /default/default/update.xml . Is there a way to stop Firefox from downloading from this document and any add-ons? Preference settings don't seem to work. I am using Selenium 3 beta 4

I set the following settings, but nothing works:

    profile.setPreference("app.update.enabled",enabled)
    profile.setPreference("app.update.staging.enabled",enabled)
    profile.setPreference("app.update.auto",enabled)
    profile.setPreference("app.update.checkInstallTime",enabled)
    profile.setPreference("app.update.silent",!enabled)
    profile.setPreference("extensions.update.enabled",enabled)

    if(!enabled){
      profile.setPreference("app.update.interval",Int.MaxValue)
      profile.setPreference("app.update.checkInstallTime.days",Int.MaxValue)
      profile.setPreference("extensions.update.interval",Int.MaxValue)
      profile.setPreference("app.update.lastUpdateTime.xpi-signature-verification",Int.MaxValue)
      profile.setPreference("app.update.lastUpdateTime.search-engine-update-timer",Int.MaxValue)
      profile.setPreference("app.update.lastUpdateTime.experiments-update-timer",Int.MaxValue)
    }

profile.setPreference("media.gmp-gmpopenh264.enabled",enabled)
profile.setPreference("media.gmp-provider.enabled",false)
profile.setPreference("media.gmp-manager.lastCheck",Int.MaxValue)
profile.setPreference("media.gmp-gmpopenh264.lastUpdate",Int.MaxValue)

Preferences seem to be set roughly in: config, but I still see the following where my tool freezes after a few dozen to 1000 tests. Due to the need to rotate the proxy and many parallel tests with two drawers, the grid is out of the question.

1475863716583   addons.productaddons    INFO    sending request to: https://aus5.mozilla.org/update/3/GMP/45.4.0/20160905130425/Linux_x86_64-gcc3/en-US/esr/Linux%204.4.0-34-generic%20(GTK%203.18.9%2Clibpulse%208.0.0)/default/default/update.xml
1475863716756   addons.productaddons    INFO    Completed downloading document
1475863717793   addons.productaddons    INFO    sending request to: https://aus5.mozilla.org/update/3/GMP/45.4.0/20160905130425/Linux_x86_64-gcc3/en-US/esr/Linux%204.4.0-34-generic%20(GTK%203.18.9%2Clibpulse%208.0.0)/default/default/update.xml
1475863717914   addons.productaddons    INFO    Completed downloading document