Firefox Nightly 63: Mozilla runs WebRender study

WebRender is a new technology that Mozilla plans to integrate in the Firefox web browser. A milestone has been reached recently as WebRender has been enabled for part of the Firefox Nightly population.

WebRender is a Servo component written in Rust that Mozilla plans to integrate into Firefox. The main idea behind WebRender is that the graphics processing unit (GPU) is used to render web content instead of the processor which has been used traditionally for that.

WebRender will replace the compositor that Gecko uses currently in Firefox. The switch from using the CPU to do the heaving lifting in regards to rendering to the GPU should improve performance of the entire process significantly.

While users should not expect major performance boosts right now in Firefox Nightly, Mozilla's aim is to improve Firefox's rendering performance significantly in the long run.

Mozilla decided to run a Shield study to test WebRender under specific criteria in Firefox Nightly. Shield studies are run to gather data, in this case how certain metrics such as crashes change on WebRender versions of Firefox compared to Firefox versions without WebRender.

The study runs on Windows 10 devices with Nvidia GPUs only and the latest version of Firefox Nightly is required as well as it won't be run on other Firefox channels such as Beta.

Img

Mozilla will select 50% of the Firefox population that meets the test criteria and enable WebRender on those systems; the remaining 50% are the control group which means that WebRender won't be enabled on those devices.

The main goal of the study is to make sure that WebRender runs within acceptable parameters when compared to the control group. Mozilla wants to make sure that regressions and crashes stay within a 5% to 10% limit.

Mozilla plans to set the preference gfx.webrender.all.qualified on eligible systems to true to enable WebRender on those systems. You can change the preference at any time, for instance when you notice rendering issues, crashes, or other issues that are caused by WebRender.

Mozilla collects issues on Bugzilla@Mozilla, and has listed some already. Users may notice higher CPU usage with WebRender enabled on YouTube, FTS drops on WebGL demo websites with the feature enabled, and that "specific images entirely coded in HTML & CSS are not corrected rendered".

The study will run for two weeks after which it ends. Data is analyzed afterward and Mozilla's next steps will be based on that analysis.

Closing Words

WebRender is a promising new feature of Firefox that is currently in development and testing phase. Mozilla wants to make sure that WebRender improves the rendering and does not cause regressions before it enables it for a larger part of the Firefox population or other channels.