Chrome is always looking for ways to speed up the web. Starting in Chrome 53, Chrome has started using Microsoft’s Profile Guided Optimization (PGO) technology to make Chrome up to 15% faster on Windows.

New tab page load time 14.8% faster
Page load (time to first paint) 5.9% faster
Startup time 16.8% faster

PGO impact on load and startup time

Chrome is a huge software project with more than a million functions in its source code. Not all functions are equal - some are called frequently, while others are rarely used. PGO uses data from runtime execution that track which functions are most common to guide optimization.

To gather this data, the nightly build process now produces a special version of Chrome that tracks how often functions are used. PGO then optimizes those high-use functions for speed, in some cases increasing the binary size of those functions. To balance out that increase, PGO also optimizes less-used functions with smaller, though slightly slower code. These trade-offs result in higher overall performance, and a smaller overall code footprint.

PGO also optimizes the memory location of the code, moving rarely-used functions away from frequently-used ones in memory. This results in more optimal use of the CPU instruction cache by avoiding caching of less-used code, increasing overall performance. There are many other tricks that PGO uses to make Chrome faster, and they add up to great results.

64-bit Chrome on Windows is using PGO as of version 53, and 32-bit Chrome is using it as of version 54. Try out the latest version of Chrome to see the difference with PGO.


Source: Chromium Blog: Making Chrome on Windows faster with PGO