Making the web faster with SPDY and HTTP/2

Four years ago we announced SPDY, an experimental protocol designed to make the web faster. It has matured quickly since then: it’s been adopted by Chrome, Opera, Firefox and Internet Explorer, dozens of server and middleware vendors, and many large sites. SPDY also became the foundation of the HTTP/2 protocol developed by the IETF, and is continuing to serve as an experimental ground for prototyping and testing new features for HTTP/2.

When we set out on this journey the objective was to make the web faster and we wanted to share our latest results. Of course, as with every aspect of performance, the numbers vary for each site, based on how it is constructed, the number of downloaded assets and dozens of other criteria. That said, we’ve observed significant performance improvements in latency—as measured by time from first request byte to onload event in the browser—across all of Google’s major web applications.

	Google News	Google Sites	Google Drive	Google Maps
Median	-43%	-27%	-23%	-24%
5th percentile (fast connections)	-32%	-30%	-15%	-20%
95th percentile (slow connections)	-44%	-33%	-36%	-28%

The above results were measured for Chrome version 29 and compare HTTPS vs. SPDY for each application across millions of real user sessions with various connectivity profiles. SPDY delivers significant latency savings for users with fast connections, at the median, and for the long tail users with high round-trip times.

In parallel with our contributions to the HTTP/2 standard, we continue to prototype further SPDY performance improvements through smarter compression, flow control, and prioritization. Our hope is that each of these will deliver better and faster SPDY and HTTP/2 protocols. We aren’t done yet—there are still many opportunities and ideas to explore to make the web faster!

Posted by Hasan Khalil, Roberto Peon, and Ilya Grigorik, SPeeDY Software Engineers