whY SLOW

Recently a friend of mine spoke to me about an amazing web development tool from Yahoo called "YSLOW"

You can download the plugin at https://chrome.google.com/webstore/detail/yslow/ninejjcohidippngpapiilnmkgllmakh?hl=en

YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages.

The tool runs tests & gives an overall performance score for websites. It categorises different problems on a scale of A to F with F being by-far the most urgent problems that need fixing.

For example, a test run on the NineMSN.com.au website gave an overall score of 68 & the most critical recommendations included making fewer HTTP requests, a CDN Network, Minify Javascripts, configure E-Tags etc.
 Some general rules to follow recommended by YSlow are listed below:
1.     Minimize HTTP Requests
2.     Use a Content Delivery Network
3.     Avoid empty src or href
4.     Add an Expires or a Cache-Control Header
5.     Gzip Components
6.     Put StyleSheets at the Top
7.     Put Scripts at the Bottom
8.     Avoid CSS Expressions
9.     Make JavaScript and CSS External
10.  Reduce DNS Lookups
11.  Minify JavaScript and CSS
12.  Avoid Redirects 
13.  Remove Duplicate Scripts
14.  Configure ETags
15.  Make AJAX Cacheable
16.  Use GET for AJAX Requests
17.  Reduce the Number of DOM Elements
18.  No 404s
19.  Reduce Cookie Size
20.  Use Cookie-Free Domains for Components
21.  Avoid Filters
22.  Do Not Scale Images in HTML
23.  Make favicon.ico Small and Cacheable