"Tor Browser seems slow... to... start"

Tor Browser on all platforms will sometimes display an information bar at the bottom of the about:tor home page after starting that says "Tor Browser seems slow... to... start" and two buttons "Learn more..." and "Don't display this again". If you click "Learn more...", you'll be taken to https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems which tells users to reset Firefox with the "Reset Firefox..." button on the about:support page. We REEEALLY don't want Tor Browser users to reset their browser, ever, because it deletes all add-ons, including Torbutton and TorLauncher. You can permanently prevent the "Tor Browser seems slow... to... start" information bar from popping up by setting the browser.slowStartup.notificationDisabled pref in about:config to true; default is false.

Firefox determines whether or not the browser is slow to start up by storing information about browser startup times to disk. To prevent this information from being stored at all, we should also set both browser.slowStartup.maxSamples and browser.slowStartup.samples to 0.