​Google: Chrome is now loading pages up to 20 percent faster than a year ago

Google has done away with a benchmark that was encouraging Chrome's V8 developers to optimize for sites that most people don't visit.
Written by Liam Tung, Contributing Writer

Google reckons optimizing its V8 JavaScript engine's performance has improved Chrome's Speedometer score by 25 to 35 percent over the past year.

Image: Google

Google is claiming speed improvements to Chrome's page-load times, now that it's using more realistic tests to guide the optimizations it makes to its V8 JavaScript engine.

Google built its V8 JavaScript engine to ensure Chrome blitzed through rich web applications, but its developers admit they've been optimizing the engine using an outdated and biased benchmark.

Last year it announced optimizations that cut V8's impact on CPU consumption, but more recently it's been working on improving Chrome load times under real-world conditions rather than its historical approach of optimizing V8 for 'peak' performance of JavaScript.

"Using insights gleaned from this real-world performance data, the V8 team implemented optimizations which improved mean page load between Chrome 49 and Chrome 56 by 10 to 20 percent, depending on CPU architecture," says Seth Thompson, Google's 'V8 track commentator'.

A key benchmark the V8 team have used over the past four years is Octane, which prioritized peak performance. Google has now decided to retire this benchmark because it offers "diminishing returns and over-optimization".

They found that peak performance benefits some heavier web applications, but for many websites a more important measure is how quickly scripts are downloaded.

Under the new approach, V8 developers have started to take snapshots of common sites such as Reddit, Twitter, Facebook, and Wikipedia.

As the V8 team explains, Octane helped V8 and other engine developers "deliver optimizations that allowed computationally-heavy applications to reach speeds that made JavaScript a viable alternative to C++ or Java".

But by 2015 achieving a high score on Octane didn't deliver significant improvements to the performance of real webpages. In fact, it ended up having the opposite effect for these pages.

"We began to notice that JavaScript optimizations, which eked out higher Octane scores, often had a detrimental effect on real-world scenarios. Octane encourages aggressive inlining to minimize the overhead of function calls, but inlining strategies that are tailored to Octane have led to regressions from increased compilation costs and higher memory usage in real-world use cases," V8 developers explained.

The new emphasis on startup optimizations is reflected in Chrome's performance in another benchmark called Speedometer, which includes JavaScript frameworks such as React, Angular, Ember, and jQuery. Chrome is now 25 to 35 percent faster than it was a year ago under this benchmark.

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