How do you keep a cutting-edge browser on the cutting-edge? Through relentless improvements. Pushing that frontier of performance is the job of the Google engineering team focused on Chrome, the popular browser which in 15 years has gone from a quiet open-source project to become a common way people experience the web.
Even at launch, in a 40-page online comic book explaining the thinking behind their new product, one of Google’s meta goals of Chrome as a browser was to be faster, start faster, and load pages faster.
“And that’s still true,” said Max Christoff, senior director of engineering for Chrome browser. “That job is never done. We’re always looking for improvements that will have the greatest impact on real-world performance for as many people as possible.”
Personalized performance
A big part of meeting that goal is optimizing for personalized performance needs. Everyone uses Chrome differently, so Chrome engineers are constantly optimizing behind the scenes, while also adding tools that enable users to tweak their browser’s desktop performance.
Two of the latest features are performance controls that can be turned on so Chrome uses up to 40 percent (10 GB) less memory to keep tabs running smoothly, and extend battery life when it’s running low. Memory Saver mode frees up memory from tabs you’re not using to provide your active websites with a better browsing experience. Energy Saver prolongs battery life by limiting background activity when your battery is at or below 20 percent.
Before a performance feature or under-the-hood improvement hits your browser, Google engineers head down a performance testing road built around two key measures: benchmarks, which happen in the lab under finely controlled conditions, and real-world performance, which measures how Chrome users in the field experience the web. Both have a distinct usefulness.
A change might mean a performance enhancement in Chrome's code, an update to how the browser looks or functions, or occasionally even a modification to a JavaScript API. Benchmarks tests measure these changes against a range of metrics, including page load speed, responsiveness to input, visual stability, and smoothness.
Since benchmarks run against a specific set of workloads, the effects of an improvement can be tracked with pinpoint precision. “If someone has an idea that might make Chrome faster or more stable, we can quickly do experiments in the lab,” said Christoff.
There are also industry accepted benchmark tools for measuring performance that Chrome engineers take into consideration and optimize against: Speedometer (measures the responsiveness of web applications), MotionMark (analyzes a browser’s ability to animate complex scenes), and JetStream (a JavaScript and WebAssembly benchmark for advanced web apps). This year, Chrome achieved its fastest load speeds across all three benchmark tests. Mid-year benchmark tests of Maglev, a new Chrome component designed to reduce overall CPU time to compile code while also saving battery life, confirmed major performance gains.
While these benchmarks test Chrome optimizations for early validation, field trials are a critical next step. “A benchmark improvement must translate to real user benefits," Christoff said. “Benchmarks validate our work under the hood, but field testing measures how the user will experience the change.”
A real-world assessment starts with Chrome Variations, a crucial A/B field trial testing framework for comparing new features. Chrome Variations enable Chrome and Chrome developers to gradually roll out features and updates to a subset of users to ensure there aren’t regressions before launching more broadly. For example, when a new feature under Memory Saver was released, engineers leveraged Chrome Variations to control the initial release to only a subset of users. This enabled Chrome engineers to validate the success of the feature on real users, providing a visual indicator without regressing the Chrome experience. By closely monitoring metrics to evaluate differences between the experimental group and control, the team was able to validate the feature was working as expected.
Said Christoff: “This gives us confidence that when we launch a change to all Chrome users, we're going to improve things and get the gains our users are looking for.”
Working with developers to establish a standard for quality
Google also provides the Core Web Vitals program, a set of metrics that measure the performance of websites from the perspective of user experience. Vitals is a great example of how Chrome is not only improving the speed of the browser, but working with developers to make their web pages more efficient and easier to load.
"Shining a light on performance can show developers where their site stands," notes Christoff.
The Core Web Vitals program offers a suite of developer tools to help assess a site's performance and how it impacts real-world user experience. The number of sites with a good user experience on all the Core Web Vitals metrics has nearly doubled in the last three years, contributing to Chrome's broader goal of delivering a great user experience across the web ecosystem.
Looking towards the next 15 years, Chrome is continuing to think about how they can make improvements to bring users a faster browsing experience and make the web work better for everyone.
“Machines change and the web evolves, so we must too,” Christoff said. “We’re doing things today that we never dreamed of just a few years ago.”
This story was produced by WIRED Brand Lab for Google Chrome.
