Allow Firefox to load multiple tabs in the background

This applies to versions 47 and up.

When you restart Firefox and restore your previous session, Firefox will wait until you select a tab before loading it. This keeps Firefox running quickly and smoothly. This is Firefox's multiprocess feature.

Is the multiprocess feature turned on?

Your version of Firefox may be using the multiprocess feature already. Follow these instructions to make sure:

  1. Type about:support in your address bar.
  2. In Multiprocess Windows, if the number is higher than zero (0), you already have the multiprocess feature activated.

If the number is zero (0), follow these instructions to turn it on:

  1. In the address bar, type about:config and press EnterReturn.

    • The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!I accept the risk! to continue to the about:config page.
  2. Search for browser.tabs.remote.autostart and double-click on the preference to set its value to true.
  3. Restart Firefox to enable multiprocess.
Allowing Firefox to load tabs simultaneously can slow down its startup.

If you've allowed an earlier version of Firefox to simultaneously load multiple tabs in the background (offered as the "Don’t load tabs until selected" check box in the PreferencesOptions menu), when you upgrade to version 47 and up, your setting will reset to allow only one tab at a time.

You can change it back through your about:config preferences (advanced users only):

  1. In the address bar, type about:config and press EnterReturn.

    • The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!I accept the risk! to continue to the about:config page.
  2. Search for browser.sessionstore.restore_on_demand.
  3. Double-click on the preference to set its value to false.
  4. Close the about:config tab to save your changes.
Allowing Firefox to load tabs simultaneously can slow down its startup.

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