Un-official Live-blogging from BlogHer 07: High Performance Websites

Tenni Theurer from Yahoo speaks on Optimizing Performance (High Performance Websites).

Response Time:
Perceived response time and Front end performance is important to understand (fast experience on your website). Everything you add to your page can slow you down.

Empty Cache versus Primed Cache:
Browsers have this notion of Cache, all the elements of a website get stored in cache. Alot of users come to a sight with an empty cache (most browsers reload elements so it is fresh). Some security programs clear cache when a computer is shut down. Empty cache has forced content designers to put value on pages. Flash and video's can effect response time. The more you take out, the faster it is for the users to access your site. You have to think not only of the users with great land line connections but also a users that may be connecting from an internet cafe in a foreign country with limited bandwith.

Golden rule: 80-90% of the end user response time is spent on the front end. Start there.

• Greater potential for improvement
• Simpler
• Proven to work

You need to design pages differently depending on if you users come from dial-up, mobile or from computer browsers.

14 Rules -

(14 Rules are all available on developers.yahoo.com or Skrentablog,  developers.yahoo.com/Yslow will provide a utility to analyze why your site runs slow). It is also worthwhile to just check out the YAHOO DEVELOPERS NETWORK that has lots of extremely helpful information.  I will post later with instructions on how to use YSLOW. We saw a quick demo and it does have specific steps you need to use.

 FYI - this information is for website developers. If you use a product that has a user interface (like Typepad), some of this information may not make sense - but is is good to know. For example, even on typepad sites you can see the initial http requests on the bottom left hand of the screen when you first bring up the blog.

See the page "Thirteen Rules" for more details (there is now 14).

1. Make fewer http requests - components being downloaded to your page (at start-up) like sitetracker.
2. Use a Content Delivery Network (instead of having thing in one location, distribute things where your users are).
3. Add an expires header
4. Gzip components
5. Put stylesheets at the top
6. Move scripts to the bottom
7. Avoid CSS expressions
8. Make JS and CSS external
9. Reduce DNS look-ups
10. Minify JS
11. Avoid redirects
12. Remove duplicate scripts
13. Configure ETags
14. Make AJAX cacheable