One of the most interesting presentations that I attended at FoWA was by Steve Souders (High Performance Yahoo!). Steve described the work that his team have done at Yahoo! to increase page load performance which led to the (perhaps surprising) discovery that 80-90% of page load times is generally consumed by front-end activity rather than back-end business logic, database access etc. By “front-end activity” Steve is referring to activity that takes place after the initial html page is retrieved such as requesting static content, parsing css/js, and actually rendering the page. The obvious conclusion is that the biggest performance gains can be achieved not by tweaking sql queries or web server config, but by focussing on front-end performance.

As a result, Steve advocates the following “14 rules”

1. Make fewer http requests
2. Use a Content Delivery Network (CDN). E.g. Akamai
3. Specify a far-future “expires” header
4. Compress text based content with GZip of deflate (achieves approx 70% reduction in file size)
5. Place CSS imports in the HEAD section at the top of the html page. (IE won’t start to render the page until all CSS has downloaded).
6. Move all script imports to the bottom of the page. (Scripts will block rendering of the remainder of the page).
7. Avoid CSS expressions (as they are evaluated every time a browser event – mouse move, resize, key press – fires, so can run tens of thousands of times per page!)
8. Use external css and js files to take advantage of browser caching.
9. Reduce DNS lookups by hosting content in as few domains as possible
10. Minify JS and CSS (removing whitespace give approx 20% reduction)
11. Avoid redirects (as they are not cached unless they have an explicit “expires” header)
12. Remove duplicate script imports (or duplicate copies of functions in different script files)
13. Configure etags correctly (or disable if not configured)
14. Cache AJaX requests where sensible (don’t automatically append a random number to the request to bypass the caching mechanism)

I’ve been a big fan of Firebug since I started writing Javascript/AJaX but this presentation alerted me to the YSlow plugin for firebug which analyses a page and generates a rating against the 14 rules.

I highly recommend reading more about these techniques on the Yahoo! developer site, and watching Steve talk about the rules in more detail. Steve has also recently brought out a book on the subject.

Last week I attended the 2-day Future of Web Apps conference at London’s ExCel. I really enjoyed this conference – there were some great speakers and I learned a lot. I hope to write a couple more posts this week covering the highlights.

One of the weirdest experiences was attending presentations by people that I’ve never met before but whose blogs I read/websites I use/podcasts I listen to or watch. It’s strange how I read BBCNews nearly every day, and on Sundays I often read The Times, but I’ve no idea who the people are that write the articles I read and yet in the tech world I know a surprising amount about the people behind sites such as GigaOM, ScriptingNews, Scobelizer (for example I know that Dave Winer has just got a Nokia N800 and the Robert and his wife Maryam have just had a new baby son, Milan).

As I was standing in the queue to collect my expo pass at FoWA I saw Leah Culver and Daniel Burka standing next to me in the line. I almost said “hi” but stopped myself when I realised that doing so would make me look like a stalker or obsessive fan and would probably make them (and me) feel uncomfortable. I can just imagine the conversation with me saying “hi, I err, like you website” and them saying “thanks” and then us both standing there nervously with nothing else to say. Is this what people mean by “star struck” I wonder?:-)

The most surreal part of the whole conference though had to be the reaction to Kevin Rose and the Diggnation live show. The first experience of this was when Kevin came on stage during the first day to give his presentation. Even while he was setting up, dozens of people went up to the stage to take his picture. I even took a picture of them taking his picture

This was nothing compared with the Diggnation show itself though. The way the crowd reacted to the appearance of Kevin and Alex Albrecht (and even producer David Prager and Digg CEO Jay Adelson) was the kind of reaction normally reserved for Hollywood actors and rock stars. At the end of the show the crown stormed the stage and there was a sea of cameraphones being held above the crowd searching for a picture of their heroes. I should say at this point that I’m a big fan of diggnation (since Ep1, oh yeah!) and seeing the London show live was hilarious.

The whole experience made me wonder whether this was nothing more than a bunch of geeks geeking-out (I include myself in that group) or something more significant. Is it another example of the social networking phenomenon making unlikely stars out of the most unlikely people and are we now in the middle of “bubble 2.0″?