Google claims it has improved Chrome scrolling by the factor 2 on Android

Chrome users who run the web browser on Android and iOS devices may have noticed that the scrolling of Chrome on Android feels jankier than that on iOS devices. Soon, Chrome users on Android will experience the same scrolling experience as their counterparts on iOS devices, as Google engineers have implemented changes in the browser that improve the scrolling experience by the factor 2, according to the company.

Google explains that it managed to reduce slow scrolling jank by 2x, which is where the number comes from. The company managed to improve scrolling by "filtering noise and reducing visual jumps in the content presented on the screen".

Engineers who analyzed Chrome's scrolling behavior on Android discovered that Chrome's predictor was not as accurate as it should be. Digging deeper, the engineers found two major differences between Chrome's implementation and that of Android.

Chrome uses Java functions with milliseconds precision whereas Android C++ MotionEvent timestamp with nanosecond precision. This was a problem, as the rounding of milliseconds could produce predictor errors when computing the velocity between event timestamps.

Resampling is also different on Android and in Chrome. Chrome uses a "simple FIFO queue of input events", which sometimes caused weird prediction issues.

Engineers at Google ran tests using different algorithms and picked the 1€ filter implementation, which, according to Google, improved the scrolling experience "visibly and drastically". The "screen tracks closely to your finger" and websites scroll smoothly, "preventing jank caused by inconsistent input events" describes Google in the blog post.

The most important question for Google users is when the improvements will land in their version of Chrome for Android. Google plans to roll it out in Chrome 116 for Android and also backport the change all the way back to Chrome 110 on Android.

Android 14 will furthermore expose the nanosecond API in the SKD so that Chrome and other applications may use it. Other Chromium-based browsers and also non-Chromium apps may also benefit from the API introduction in Android 14.

Closing Words

Google claims that the scrolling improvements are noticeable visually but also when looking at the numbers, both on low-end and high-end devices.

Now You: how is the scrolling behavior of your favorite mobile browser?

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