Google Chrome 53 Secretly Received a 15% Speed Boost on Windows PCs

Google revealed on Monday that Chrome had secretly received a speed boost on Windows since the start of September after its engineers had integrated a technology known as Profile Guided Optimization.

Known as PGO, but also as Profile-Directed Feedback (PDF) and Feedback-Directed Optimization (FDO), this technology describes a method of compiling source code into applications by relying on "profiles."

Google engineers said they went through Chrome's entire source code and divided code functions based on how often Chrome calls on the routines.

High-use functions receive more optimization, so they execute faster, even if this results in an increased binary size. Low-use functions are also optimized, but the focus is put on cutting down their size in the outputted binary, instead of speed of execution.

Google says it added PGO support to Google Chrome 64-bit in Chrome 53, released at the start of September, and for the 32-bit version of Chrome 54, released at the start of October.

Chrome is not the first browser to feature PGO. Mozilla has deployed PGO with Firefox since August 2013.

According to internal benchmarks, Google says that PGO support in Chrome has resulted in several speed boosts, described below.

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

Besides the speed improvements already added to Chrome on Windows in v53 and v54, Google also announced two weeks ago that Chrome 55, set for release any day now, will use far less memory thanks to changes in V8, the browser's JavaScript engine.

Detailing the improvements in a technical blog post, Google engineers said that by modifying how V8 handles JavaScript heap size and off-heap zone memory, they managed to cut down the memory Chrome uses between 35% and 50%. Images of the benchmark results are available below.

But Chrome is not the only browser that has received a startup speed boost. Opera 41, launched around a week ago, also features improvements to the startup routine.

Opera engineers say that Opera 41 is 86% faster compared to Opera 40 when starting a previous browser session with 42 tabs, and 50% faster when starting browser sessions with 10 tabs. These results are only relevant to people who configure Opera to use sessions and re-open from where they left off the last time.