Lately in some of my writing projects I’ve had to hunt down sources to demonstrate the importance of web page speed. Usually a quick Google search will pull up some pretty good ones, and I have a few others on file that I can refer to.
I thought I would put together a roundup of some of the ones I’ve been able to find. Web development bloggers, who are constantly promoting the importance of web page speed, should have these types of authoritative sources at their fingertips.
So consider this post the collective evidence for the importance of page speed. Posts are listed from oldest to newest.
- Google’s Marissa Mayer: Speed wins
Dan Farber, ZDNet (November 9, 2006) - Page Load Times vs Conversion Rates
Gabriel Svennerberg, In usability we trust (December 18, 2008) - Speed Matters
Jake Brutlag, Google Research Blog (June 23, 2009) - Bing and Google Agree: Slow Pages Lose Users
Brady Forrest, O’Reilly Radar (June 23, 2009) - Velocity and the Bottom Line
Steve Souders, O’Reilly Radar (July 1, 2009) - More on how web performance impacts revenue…
Jesse Robbins, O’Reilly Radar (October 1, 2009) - Business impact of high performance
Steve Souders, stevesouders.com (October 6, 2009) - How Loading Time Affects Your Bottom Line
Sean Work, KISSmetrics (April 28, 2011) - Speed Is A Killer – Why Decreasing Page Load Time Can Drastically Increase Conversions
Sherice Jacob, KISSmetrics (May 10, 2011) - Page load time – the online business killer
David Mercer, Business Insider (May 24, 2011) - For Impatient Web Users, an Eye Blink Is Just Too Long to Wait
Steve Lohr, NYTimes.com (Feb. 29, 2012) - 37 Lessons I’ve Learned on the Performance Front Lines
Joshua Bixby, Web Performance Today (Oct. 5, 2012) - Site speed: case studies, tips and tools for improving your conversion rate
David Moth, Econsultancy (October 23, 2012)
If you know of any other good sources that discuss why page speed matters, add them to the comments and I’ll continually update this post. And keep in mind, these are sources that show why page speed matters not how to make pages faster.
So if you’re heading to a client meeting or want to discuss with your boss why it’s wrong to polyfill some CSS3 or HTML5 feature so it works in IE6/IE7/IE8, this might be a good way to show the potential effects of slowing down the slowest browser.

Thanks for this, really useful information.
Dig the roundup of articles. Before I finished the redesign/re-engineering of my site, I grabbed the PageSpeed addition to Firebug and heeded it’s warnings. After quite a few hours of optimizing the front-end scripting and server output, I managed to get PageSpeed scores of 90-95. http://focus97.com
Now we do the same for client sites. It’s tough to gauge the true ‘experience’ from a user/visitor’s perspective, but average visit times have increased, perhaps owing to the speed not being a distraction (i.e. when it was slower).
Hi,
You may find this article and infographic interesting;
http://www.shiftscape.com/website/the-need-for-speed/
Dan
Thanks, these are really useful links and some helpful advice for shrinking load times. I know its important to cater for the slowest but I still feel like should design for the fastest – survival of the fittest! If you can’t keep up, get out the race… or update your browser or your hardware! Wrong, I know, but everyone is entitled to an opinion.
Thanks, very useful article :-) Good links, and a lot of information on shrink loading time. Unfortunatly, we do’nt have any good tip.
As a long time web application developer I’ve found that working on a fast application lets me work so much faster. The faster I can load up and get to a page, the faster I can make changes on it or fix bugs, etc. Maintaining a slow application just slows everything down, testing, development, etc.
Very applicable content! There are many times where I am very frustrated by slow sites. Many people are unwilling to spend the extra cash to ensure speed, but it is ultimately worth it when it comes to web design and general website formation!
thank you for this Article
Very good website !
I’ve added this one to the list:
http://www.nytimes.com/2012/03/01/technology/impatient-web-users-flee-slow-loading-sites.html
A relevant list by Steve Souders:
Performance Tools
More relevant links:
http://blog.chriszacharias.com/page-weight-matters
http://www.bookofspeed.com/
https://developers.google.com/speed/
And more:
How Does Reducing JavaScript Requests & Minifying JavaScript Impact Site Performance?
Creating a Performance Culture
Related:
http://www.webperformancetoday.com/2013/01/31/web-performance-101-developers/
Two good slide decks on this topic:
http://www.slideshare.net/joshfraz/sept-2012rumtalk
http://www.igvita.com/slides/2013/breaking-1s-mobile-barrier.pdf