Mozilla is adding a new feature to Firefox 66. Scroll Anchoring should eliminate unexpected page content jumps that happen when images and ads are being asynchronously loaded at the top of the page, making you scroll the page down.
The new Scroll Anchoring feature should resolve the issue. With Scroll Anchoring, you can start reading a page with a huge number of images and other media elements without waiting for all blocks to be rendered on it. A new tweet reveals that the change has already landed on the Nightly version of the browser:
— Firefox Nightly (@FirefoxNightly) January 14, 2019
Scroll Anchoring is not an exclusive feature of Firefox. It is part of a web standard, which is a work-in-progress as of this writing. However, Google Chrome has it implemented in the Blink engine starting with version 56.
To try this feature in action, you need to install the latest Nightly version of the browser. It is recommended that you create a separate profile for it as described in the article
The Scroll Anchoring feature is a long-awaited and welcomed addition to the browser. It will reach the stable branch of the browser on March 19, 2019 with version 66.