Chrome’s preloader delivers a ~20% speed improvement!

Wait, what’s a preloader? The preload scanner is designed to look ahead in the requested document and discover critical resources (CSS, JavaScript, images), such that they can be dispatched as soon as possible - this helps reduce the overhead of network latency. All modern browsers use this or similar technique to help speed up your browsing.

How do I design my pages to take advantage of the preloader? Simple, specify your critical resources in the document (aka, HTML). The PreloadScanner does not (and cannot) speculatively execute JavaScript, so if you are scheduling resources from JS, then you’re not getting the benefit of the PreloadScanner. This is why declaring your resources in the HTML markup is so important for performance!

Below results are a direct comparison with Chrome preloader ON vs. OFF, run against ~2000 sites. For full and raw results, see: - courtesy of +Patrick Meenan and +James Simonsen.

Curious to learn more about Chrome networking performance? Check out “High Performance Networking in Google Chrome” @
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