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The latest Firefox revs up browsing by stitching more threads into your CPU


The latest version of Mozilla’s Firefox web browser is now available for PC (v58) and Android (v58) devices. The list of new features is small on the PC version, as the company mostly focused on improving the software’s overall performance. According to the company, Firefox now uses a method called off-main-thread painting that relies on a new, dedicated CPU thread to provide fast, smoother page loads. 

Prior to Firefox 58, the Quantum-branded desktop browser presented web pages using four steps: Making the display list, assigning items to layers, rasterizing each item on their assigned layer, and compiling everything into the page you view within the browser. To render the page at 60 frames per second, the entire list — such as processing input events and JavaScript code — must be accomplished in 16 milliseconds. 

Firefox Quantum performs these four stages in two processes or threads. The first “main” thread consists of the display list, layer assignments, and rasterization. This thread pushes its results to a second thread for composition and then restarts its three-stage process. But with Mozilla’s new method, the browser relies on a third “paint” thread to rasterize every element of the web page. 

Thus, the flow consists of the display list and layer assignment in the first main thread, rasterization in the second, and composition in the third. The overall page rendering is now faster because once Firefox sends data to the paint/rasterization thread, the main thread can process the new JavaScript and input events. Of course, that is just a simple explanation, as the details get a bit more technical when Firefox needs to render complex pages. 

“In Firefox 58, rasterization will consume less of the frame budget on average,” Mozilla says. “Similarly, in Firefox 57, rasterization is a significant slice — 50 percent of the paint cycle or more — 21 percent of the time. In Firefox 58, that scenario occurs only four percent of the time!” 

According to a chart, Firefox Quantum 58 can render pages with heavy JavaScript at 40 frames per second versus Firefox 57 running the same page at 31 frames per second. Mozilla expects the rendering speed to become even faster once the company integrates its next-generation web page renderer, aptly called WebRender, into Firefox. Mozilla will provide additional information in the coming months. 

Outside the new off-main-thread painting process, Firefox Quantum 58 has a new way the browser caches and retrieves JavaScript called JavaScript Startup Bytecode Cache. Firefox also now enables you to copy and paste screenshots directly to the clipboard, and grab screenshots when surfing the internet in Private Browsing mode. Tracking Protection is also now available to Nepali-speaking Firefox customers. 

As for the latest Firefox browser for Android, Mozilla revised the bookmarking feature with a full screen to better view and organize your favorites and folders. The Android version also now provides better support for Progressive Web Apps, which are essentially websites that work like an app within any browser on any device, whether they’re used on a desktop PC or Android-based phone. You can now access these “apps” directly from your home screen outside Firefox. 

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