Zoompf's Web Performance Blog

Note: Archived Content

This is the archived version of the Zoompf blog. Since our acquisition by Rigor, all our new research and posts on web performance are being published on The Rigor Blog

SPDY coming to Safari, future versions of IE

 Billy Hoffman on June 6, 2014. Category: random

SPDY, the next generation web transport protocol, continues to gain ground and acceptance. I’ve been watching SPDY very closely and writing extensively about it for the last few years. Last year I broke the news that Facebook had adopted SPDY, ahead of other tech news sites like Wired. Zoompf has also built SPDYCheck.org, to help developers test their website for SPDY support and help them resolve any problems. This past week saw two great news announcements about SPDY that I want to share.

Internet Explorer commits to SPDY. Again.

I know what you are thinking. Didn’t Microsoft announce a year ago that IE would adopt SPDY? In fact they did. Microsoft announced in spring of 2013 that IE would support SPDY. And it was fantastic news at the time. Unfortunately, as I have discussed before, Microsoft only ships new features when it ships a new major version of IE. All those monthly updates to IE? They are only security patches and provide no new features, functionality, or support for new web standards.

When IE11 finally shipped in October 2013, its promise to deliver SPDY had diminished somewhat. IE11 does support SPDY, but only on Windows 8.1. IE11 on Windows 7 does not support SPDY. So, while IE11 has a market share of 17% right now, all of those installs of IE11 can’t use SPDY. Can we figure out what percentage of IE11 can use SPDY? We can try!

IE11 runs on Windows 7 and Windows 8.1 (as well as a version of Windows Server, which accounts for so little web browsing traffic we will ignore it). IE11 does not run on Windows 8. Lets look at the OS market share numbers from NetMarketShare:


Windows 7 has 50% market share, and Windows 8.1 has 6.35%. We know that 100% of Windows 8.1 installs have IE11, but we don’t know the percentage of Windows 7 users that have installed IE11. If we conservatively estimate that 50% of Windows 7 users have IE11 (reasonable given that Microsoft has been automatically upgrading Windows 7 users to IE11 via Windows Update), then that means 20% of IE11 users are on Windows 8.1, and 80% are on Windows 7. In other words, we conservatively estimate that only 20% of IE11 installs can actually communicate with SPDY.

Needless to say, the promise of SPDY support in IE has fallen short somewhat. Today, the vast majority of IE11 users cannot use SPDY.

Luckily this is set to change. Last week Microsoft updated its IE status website and now lists HTTP/2 support as “in development”. As we know, HTTP/2 uses SPDY as its base. Presumably this means the next version of IE will support SPDY and HTTP/2. This is great news. IE is doubling down on its commitment to SPDY. In additional to supporting SPDY and HTTP/2 in new versions, as time passes, the market share numbers of Windows 8.1 should (hopefully) increase, meaning more IE users can take advantage of SPDY.

Apple announces SPDY support in Safari 8

Chrome, Firefox, and Opera have all supported SPDY for a number of years. As we have seen, IE is making slow yet steady progress s well. Safari has long been the last major browser without SPDY support. All that changed on Monday at Apple’s WWDC 2014 event.


Apple announced that its next version of Safari will support SPDY. In fact, of the 6 new features Apple chose to highlight SPDY support was #2, behind only WebGL. Safari 8 will ship with OS X Yosemite, which is “coming this fall.” This means that, by the end of 2014, all major browsers will support SPDY!


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