Think Firefox Quantum is fast? Try Firefox 58, out this week, says Mozilla

The incoming Firefox 58 brings faster page loads thanks to a new compiler and streaming compilation, reports Mozilla.

Mozilla is promising more speed improvements in the forthcoming Firefox 58, building on the new engine introduced in Firefox 57, known as Quantum, which is better at exploiting multicore CPUs.

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Firefox 58 will be faster at compiling WebAssembly code coming in from the network thanks to 'streaming compilation' -- which allows code to be compiled and downloaded in parallel -- and a faster two-tiered compiler.

WebAssembly code works with JavaScript to offer near-native performance to web apps. Safari and Edge recently added support for WebAssembly, broadening existing support for the .wasm format from Chrome and Firefox.

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Streaming compilation and the new compiler allow Firefox 58 to compile code faster than the network can deliver packets, thus removing the main bottleneck to faster page loads that involve downloading a lot of JavaScript, according to Lin Clark, an engineer on the Mozilla Developer Relations team.

In the past, web performance was constrained by the network, Clark said, but the new bottleneck is the CPU and the main thread. Firefox 58 takes the burden off the main thread and makes better use of a CPU's time.

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Mozilla says the added speed in Firefox 58 comes partly from a new compiler that loads WebAssembly files faster than the equivalent-sized JavaScript files.

Image: Mozilla

The new compiler in Firefox 58 with streaming compilation will help the browser load WebAssembly files faster than the equivalent-sized JavaScript files, according to Clark.

"If you start compiling the code earlier, you'll finish compiling it earlier. That's what streaming compilation does... makes it possible to start compiling the .wasm file as soon as possible. When you download a file, it doesn't come down in one piece. Instead, it comes down in a series of packets."

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Meanwhile, Firefox 58's two-tiered compiler aims to get around the compiling time trade-off between optimizing code while compiling or compiling non-optimized code.

"We can have the best of both of these worlds. If we use two compilers, we can have one that compiles quickly without too many optimizations, and another that compiles the code more slowly but creates more optimized code," writes Clark.

Firefox 58 is currently in beta and scheduled for release on January 23, and Mozilla hopes the latest speedups will tempt more former users to give Firefox another chance.

Previous and related coverage

Mozilla: Firefox 57 is so fast we're calling it Firefox Quantum

Firefox Quantum will test whether Mozilla's efforts to modernize its browser can pay off.

Why is Firefox Quantum so fast? Mozilla reveals a tweak that turbo-charged its browser

Mozilla's latest version of its Firefox web browser gets a performance boost from a privacy feature.

Firefox Quantum: 170 million installs so far, as more Chrome users jump ship

Firefox sees a bump in installs from Chrome users after the big Quantum overhaul.

3 awesome features coming to Firefox that you can get right now (CNET)

The upcoming Firefox 59 will help you stop sites from asking for permission to send you notifications and know your location, but you can stop these right now in the current build of Firefox with a little digging.

How to manage Firefox Quantum site permissions (TechRepublic)

Jack Wallen walks you through the process of managing both default and site permissions with Firefox Quantum, so you can enjoy a more secure and reliable browsing experience.