How to Boost the speed of your Magento Site ?

One of the drawbacks of Magento is currently its speed if default configuration is used. There are certain ways of making it run faster.
Let’s start speeding up Magento!

First step, edit .htaccess file.

Enable Output Compression

This section will turn on the apache mod_deflate module, which compresses text, css, and javascript before it is sent to the browser. This results in a smaller download size. To enable, simply uncomment the appropriate lines so that it looks like the following:

############################################
## enable apache served files compression
## http://developer.yahoo.com/performance/rules.html#gzip
 
    # Insert filter on all content
    SetOutputFilter DEFLATE
    # Insert filter on selected content types only
    AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript application/javascript
 
    # Netscape 4.x has some problems...
    BrowserMatch ^Mozilla/4 gzip-only-text/html
 
    # Netscape 4.06-4.08 have some more problems
    BrowserMatch ^Mozilla/4\.0[678] no-gzip
 
    # MSIE masquerades as Netscape, but it is fine
    BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
 
    # Don't compress images
    SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-gzip dont-vary
 
    # Make sure proxies don't deliver the wrong content
    Header append Vary User-Agent env=!dont-vary

Enable Expires Headers

Browsers use Expires headers to determine how long a page component can be cached. Static components, like images, should have far-future expires headers, but truthfully, all page components should have expires headers. To turn this feature on, just uncomment the appropriate line and add “ExpiresActive On” right above it. See below:

############################################
## Add default Expires header
## http://developer.yahoo.com/performance/rules.html#expires
 
    ExpiresActive On
    ExpiresDefault "access plus 1 year"

Keep in mind, if you use a far future Expires header you have to change the component’s filename whenever the component changes. More info http://developer.yahoo.com/performance/rules.html

Disable ETags

ETags are a way for browsers to validate cached components across subsequent visits. They can slow down a site served from a cluster if the cluster hasn’t implemented them properly. It is best to just turn them off as follows:

############################################
## If running in cluster environment, uncomment this
## http://developer.yahoo.com/performance/rules.html#etags
 
    FileETag none

Now, from Magento admin side make sure that you combine JS and CSS files.

• Magento admin -> System Configuration -> Developer -> Under “Javascript Settings”, change “Merge Javascript Files” to YES.
• Magento admin -> System Configuration -> Developer -> Under “CSS Settings”, change “Merge CSS Files” to YES

Clear the cache.
Use CDN if it is possible, please note combining CSS/JS when using CDN will cause CSS/JS to “break” until the CDN updates completely.

Enable Flat Catalog

Magento uses the EAV model to store customer and product data. This enables these objects to be incredibly extensible, but results in longer SQL queries and more reads. Enabling the Flat Catalog for Categories and Products merges product data into one table, thereby improving performance. Generally, all stores should enable Flat Catalog for Categories.
More information you can find following yslow user guide http://yslow.org/user-guide/, here you can find more tutorials and resources to follow.
Happy speeding