Yahoo!'s Latest Performance Breakthroughs

导读：

　　March 17, 2008

　　Stoyan Stefanov made an appearance last week at the PHP Quebec Conferencein Montreal. His sessiondebuts Yahoo!’s latest research results and performance breakthroughs. He covers the existing 14 rules, plus 20 new rules for faster web pages. We’ve categorized the optimizations into: server, content, cookie, JavaScript, CSS, images, and mobile.

　　After YSlow "A"?

　　If your page isn't getting an "A" in YSlow, I recommend that you tackle those recommendations first. However, if you're getting an "A" and looking for more ways to optimize your web pages, here are 20 new recommendations to accelerate the end-user's experience. Stay tuned, you'll be hearing more about YSlow and these rules at Yahoo! Developer Networkand Yahoo! User Interface Blog.

　　1. Flush the buffer early [server]

　　2. Use GET for AJAX requests [server]

　　3. Post-load components [content]

　　4. Preload components [content]

　　5. Reduce the number of DOM elements [content]

　　6. Split components across domains [content]

　　7. Minimize the number of iframes [content]

　　8. No 404s [content]

　　9. Reduce cookie size [cookie]

　　10. Use cookie-free domains for components [cookie]

　　11. Minimize DOM access [javascript]

　　12. Develop smart event handlers [javascript]

　　13. Choose <link> over @import [css]

　　14. Avoid filters [css]

　　15. Optimize images [images]

　　16. Optimize CSS sprites [images]

　　17. Don't scale images in HTML [images]

　　18. Make favicon.ico small and cacheable [images]

　　19. Keep components under 25K [mobile]

　　20. Pack components into a multipart document [mobile]

　　Many thanks to all the developers at Yahoo! that have directly or indirectly contributed to this list - you know who you are (see credits at the end of Stoyan's presentation). We share our findings so that others can join us in accelerating the user experience on the web.

　　Tenni Theurer

　　Yahoo! Exceptional Performance

　　Posted at March 17, 2008 4:02 PM

　　

　　Comments

　　Great, just what I need- another carrot to chase :)

　　Posted by: Rob at March 17, 2008 5:48 PM

　　Any idea on when we can look forward to seeing these new recommendations make their way into YSlow?

　　Posted by: Dan at March 17, 2008 10:17 PM

　　Hi Dan, I cannot make any promises right now, but definitely expect to see more details on the new best practices as well as integration with YSlow.

　　Posted by: Stoyan at March 18, 2008 10:27 AM

　　Use PNGs? Really? Until IE6 is at the same level as IE5 is right now (almost unused), I still say they are more trouble than they're worth.

　　Posted by: Eric B at March 18, 2008 5:58 PM

　　Stoyan, I'm super happy to learn that you'll both integrate these new techniques into Yslow *and* write more in details about these. I can't wait to read more !

　　Thank you !

　　Posted by: Louis at March 19, 2008 4:48 AM

　　Love the list. I'll try to integrate these into my client's sites.

　　Any chance a forum discussing Yslow or something to that affect? I never understand why my client's sites score as low as they do in it. For example, our recently launched site Sensible Moves (http://www.sensiblemoves.com/) receives an F for 'Add an Expires Header'. It is rare in my situation to be able to add an Expires header on every HTTP request. I think it's unfair to give an F for 5 out of 18 HTTP requests needing it. Also, getting a B for putting CSS at the top for document being added with document.write seems nitpicky.

　　Posted by: Brian LePore at March 20, 2008 5:33 AM

　　Could you link the actual slides so they can be downloaded? SlideShare is obnoxious enough to require a log-in for this privilege.

　　Posted by: Ben at March 20, 2008 7:30 AM

　　Ah almost full A's besides the CDN and one gzip thing.

　　However the gzip thing is annoying, 1 serve one css without gzip because it is larger when gzipped.... not very nice of yslow to detract points from me for serving a smaller file.

　　Posted by: bartwe at March 20, 2008 9:38 AM

　　@Brian: You can participate in our performance mailing list for discussions regarding YSlow and other performance-related topics.

　　Posted by: Tenni Theurer at March 20, 2008 10:01 AM

　　http://tech.groups.yahoo.com/group/exceptional-performance/(our performance mailing list)

　　Posted by: Tenni Theurer at March 20, 2008 10:02 AM

　　On Slide 16 you reference Amazon's Simple Storage Service (S3) as a Content Delivery Network. While S3 is a good origin server and will help optimizers set the appropriate headers for cached content, there is currently no "network" component to its delivery. S3 customers can place their files into a single storage location in either the United States or in Europe.

　　Posted by: Niall Kennedy at March 20, 2008 10:52 AM

　　@Brian - First, ignore Math D and sho's comments because they do nothing but detract from the performance of this page. Code can usually be improved and the fact that you're here is encouraging, especially if you maintain an authoring tool. If this tool seems "nitpicky" that's because this is *the* tool to pick nits! :)

　　Posted by: Dave L at March 21, 2008 8:50 AM

　　Thanks for the presentation! It's really useful and YSlow was helping me identify all various issues related to web performance.

　　I've posted the presentation to TechPresentations.org: http://www.techpresentations.org/High_Performance_Web_Pages- feel free to add more info about it, your team or just related topics. It'll be great if there was PDF/PPT or maybe even video of the talk available.

　　Thank you,

　　Sergey

　　Posted by: Sergey Chernyshev at March 22, 2008 10:43 PM

　　The first 14 rules are easy enough to implement if you have control over your site. I'm looking forward to tackling the next 20. The first set of rules is so simple, in fact, that anyone should be able to benefit from following it.

　　Posted by: Kari P?til? at March 24, 2008 12:38 PM

　　Really good article. I have increased my performance about 3 seconds.

　　Thanks.

　　Posted by: Leonidas at March 25, 2008 7:49 AM

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http://developer.yahoo.net/blog/archives/2008/03/yahoos_latest_p.html