Zen Browser (based on Firefox) config changes for better speed, privacy, and security.
Inspired from the config tweaks Betterfox for Firefox Browser.

Zen's default preferences are already based on Betterfox (as mentioned here).
But there are a few differences, which are covered by Better Zen.

Tested with Zen version 1.11.3b Based on Betterfox version 135

1. Download the Better Zen user.js file from here. (Right Click -> Save Link As...)
2. Open a Zen Browser window. In the URL bar, type about:profiles and press Enter.
   This will open the page for managing all browser profiles.
3. Click on the Create a New Profile button to create a fresh profile.
   It is recommended to start fresh to avoid overriding any existing profiles.
4. Follow the steps in the Create Profile Wizard and give your profile a cool name like Better Zen.
   Your profile will be added below the existing profiles on the about:profiles page, and will be set at the new Default Profile.
5. Under the new profile's name, in the row labelled Root Directory, use the Show in Finder button (Mac OS) to open the profile's directory in a new finder window.
6. Copy the previously downloaded user.js file and place it in the new profile's root directory.
7. Back in the Zen Browser, under the new profile's name, use the Launch profile in new browser button to open a new Zen Browser window using the new profile.
8. You'll be treated with the first launch welcome screens, letting to choose your theme, search engine, etc. for this new profile.
9. That's it. You can now close the original Zen Browser window with the older profile, and start enjoying your Better Zen Browser with enhanced speed, privacy and security.