Steve Souders: "High Performance Web Sites: 14 Rules for Faster Pages"
--video
http://www.oreillynet.com/fyi/blog/2007/09/steve_souders_high_performance.html

Rule 1: Reduce #HTTP requests.

concatenate style sheets and JS files.
image maps
CSS sprites

Rule 2: Use a content delivery network
split static content to edge servers

Rule 3: Add an Expires header

for all static content

Rule 4: Use gzip components
90% of browsers support compression
70% compression on html documents
(web server configuration)

Rule 5 Put style sheets at the top
All style sheets need to downloaded before rendering starts.

In IE use LINK not @import

Rule 6: Move scripts to the bottom.
scripts block rendering of everything below them.
script defer is NOT a solution

Rule 7: Avoid CSS expressions

problems are expressions are evaluated many times (e,g, mouse moves)

One time expressions OK if can code it.
Or add an event handler and tie to that. (Saves many executions).

Rule 8: Make JS and CSS external

inline: HTML document is bigger, but

external: more HTTP requests, but cached variables

rule 9: reduce DNS lookups
these block parallel downloads

Rule 10: Minify Javascript
Remove white space and comments
Also obfuscate (minify is safer)

Rule 11:avoid redirects
301 & 302 status codes

Rule 12: Remove duplicate scripts
cause extra HTTP requests

Rule 13: Configure ETags
But be careful of incompatibility between web server instances. (Some use iNode, which may differ between servers).

(Or turn off)

Rule 12: Make AJAX cacheable
a personalized response should be cacheable.
(i.e. still use expires)
Or use different page name (e.g. address book page URL may contain modification date.
So if had been modified, then link is different and new copy downloaded).




http://developer.yahoo.com/yslow




http://www.oreilly.com/catalog/9780596529307/index.html#details
High Performance Web Sites : Essential Knowledge for Front-End Engineers 
By Steve Souders
First Edition September 2007  
Pages: 168 (More details)
ISBN 10: 0-596-52930-9
ISBN 13: 9780596529307