I know it’s bit late but I wanted to mention my favorite panels at SXSWi that attend this past spring.
“Even Faster Websites” presented by Steve Souders which he is well know for creating YSlow and now Google Page Speed. If you’re not familiar with these two Firefox plugins then you should definitely check them out.
What I really enjoyed about his presentation was how technical it was, which most panels I went to were mostly theories and best practices. What he focused on that day was javascript which has become more and more heavily used with today’s websites and definitely with things we have done here. Here are few key things he touched on.
Script blocking which is when a browser downloads JS (javscript) and that JS filet will stop everything from loading, images, css files and iframes. The browser will then also wait till the JS is executed and then finish downloading the other assets.
IE7 only allows 2 connections per hostname. What this means in a nut shell is the browser will only download 2 files at the same time from the same domain name. People get around this by what they call domain sharding, where you have multiple sub domains loading assets for one site. For instance Amazon.com has a.amazon.com, i.amazon.com and so on. With this technique though you still have to wait for JS to load and execute before the browser can continue downloading the other assets.
A couple other things Steve mentioned were iframes share the same connection pool with the parent window. Meaning if the iframe is loading 2 things already then the parent element can’t load it’s assets. Also stylesheets in the parent parent window also block iframes and/or it’s resources.
Now Steve did mentioned a few good ways to address these issues. Put your JS at the end of your web page, just right before the closing body tag. Use the script DOM element or script onload technique to load your JS. I’m not going to explain the process of implementing these 2 techniques because they get pretty technical but you should look at his reasoning in the powerpoint.
Last but not least are few other things to help speed up your site. Gzip your files, sprite your images and flush your document. Now I’m off to make the web even faster!