Off-Main-Thread Compositing Is Coming With Firefox 40 For Linux
Written by Michael Larabel in Mozilla on 6 July 2015 at 09:18 AM EDT. 15 Comments
At the end of last week the first beta of Firefox 40 was released, now that Firefox 39 shipped. With Firefox 40 comes some exciting changes for Linux users.

In particular, one of the most sought-after items for Firefox 40 on Linux is the Off-Main-Thread Compositing support. As explained by Eric Griffith in The State Of Various Firefox Features, "The idea behind Off-Main Thread Compositing is that an event or command that doesn't affect something user-visible should not slow down the entire browser, especially not animation and video playback...This feature is currently enabled on all platforms except Linux where ther are 5 open bugs against the feature. Once it is enabled it is assumed that Linux will retain only basic support due to outstanding bugs and quality problems with video drivers."

That was back in May and since then the Firefox developers have corrected the OMTC-related bugs on Linux, which means it can now ship enabled by default for the Linux builds. The 40.0 beta release notes mention, "Improved scrolling, graphics, and video playback performance with off main thread compositing (GNU/Linux)."

Other Firefox 40 changes include Suggested Tiles based on your recent browsing history, a new style for the add-on manager, asynchronous CSS animations to be smoother and more reliable, less memory and faster painting of scaled down JPEG images, and various new HTML5 and developer features.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter or contacted via

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