Page Performance in HTTP1 vs HTTP2

Last updated on July 31, 2015 in Development

When I think about HTTP2, I think about web performance and page load times. There is a lot more to HTTP2 like server push but I am very curious about the impact on website speed. How do the webperf metrics change when a page is delivered with HTTP2 instead of HTTP1? Let’s check out a waterfall comparison via WebPageTest:

First, we have an web page with a bunch of content served via HTTP1.1:

As you can see from the waterfall above, the Chrome browser loads 861 DOM elements in 5.5 seconds. Now, here are the results for the same page served via HTTP2:

Same 861 DOM elements loaded in 2.4 seconds. Also, this one is over https which shows additional SSL negotiation which adds a bit to page load and start render. It might also not be the most typical page but serving it over HTTP2 improves page speed by over 3 seconds! When will Apache and nginx support HTTP2?

External:

HTTP2 and Google Analytics
HTTP2 Changes Everything
Go + HTTP/2
Nine Things to Expect from HTTP/2