I recently gave a talk at SMX Advanced in Seattle about how to make websites run faster. Various statistics cited by the presenters indicated just how important site speed is. Every second of latency cuts conversion (or sales) by 10 – 17 percent. Users typically head for the back button if a page doesn’t appear within 3 seconds. Fast sites give the user a feeling that they are in control, improving trust.
Most people think a bigger server, shorter HTML code, or smaller images is the secret to speed. That’s usually not the case, according to my experiments. The main cause of latency is distance between the server and the user, and the number of http requests required to assemble the page. Server and software configurations may also be important.
Every image, CSS, and JavaScript file generates another http requests. Browsers typically process 2 – 5 requests in parallel. It is not uncommon to find pages that generate 50, 100 or even 275 requests. Processing all those requests one after another can take considerable time if the distance from user to server is a few thousand miles because information never goes faster than the speed of light, about 186,000 miles per second. A user in Amsterdam looking at a complex page with 275 requests served from San Jose will typically suffer 4.2 seconds additional latency or worse.
One secret to speed is using a smart content delivery network, such as Cloudflare, to reduce the distance information needs to travel, minimize requests, and optimize files sizes. Cloudflare caches static resources a numerouse locations around the world to serve users from a nearby data center. Another tactic is to simplify web page design to minimize the number of files called per page. CSS sprites can be a big help, as well as eliminating unnecessary objects. Careful design focuses attention on a few things that matter, and leaves out the cruft that is just a distraction and source of slowness.
My presentation below containes a bunch of case studies and identifies tools you can use to analyze and improve your site speed. Feel free to contact me with any questions. I’m @jehochman on Twitter.
