Optimizing page load times using mod_deflate, mod_expires, and ETag on Apache2
Posted by: Brian Gilbert
If you are a front-end web developer or host your own websites I highly recommend you take the time to read the following books by Steve Souders of Yahoo:
- High Performance Web Sites: Essential Knowledge for Front-End Engineers
- Even Faster Web Sites: Performance Best Practices for Web Developers
They are both quick reads and if you are in the industry they should be interesting to you as well
You should also be using the YSlow Firefox extension along with Firebug which enables you to test your sites easily against the precepts outlined in Steve Souders first book.
And now here are the changes I made on my server that improve end user experience by decreasing page load times on sites, I encourage you to try it as well.
GZip compression using mod_deflate
First enable the deflate module, using debian this can be done as follows
a2enmod deflate
Then edit the deflate.conf file located in /etc/apache2/mods-available/deflate.conf
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/x-httpd-php
AddOutputFilterByType DEFLATE application/x-httpd-fastphp
AddOutputFilterByType DEFLATE application/x-httpd-eruby
DeflateCompressionLevel 9
# 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
# Setup custom deflate log
# DeflateFilterNote Input instream
# DeflateFilterNote Output outstream
# DeflateFilterNote Ratio ratio
#
# LogFormat '"%r" %{outstream}n/%{instream}n (%{ratio}n%%)' deflate
# Example of log file (add to vhosts)
# CustomLog logs/deflate_log DEFLATE
</IfModule>
Expires headers using mod_expires
First enable the module
a2enmod expires
Then edit (I had to create this file) the expires.conf file located in /etc/apache2/mods-available/expires.conf
# ExpiresDefault "access plus 2 months"
ExpiresByType image/x-icon "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType application/pdf "access plus 1 month"
ExpiresByType audio/x-wav "access plus 1 month"
ExpiresByType audio/mpeg "access plus 1 month"
ExpiresByType video/mpeg "access plus 1 month"
ExpiresByType video/mp4 "access plus 1 month"
ExpiresByType video/quicktime "access plus 1 month"
ExpiresByType video/x-ms-wmv "access plus 1 month"
ExpiresByType application/x-shockwave-flash "access 1 month"
ExpiresByType text/css "access plus 1 hour"
ExpiresByType text/javascript "access plus 1 hour"
</IfModule>
Configure ETags to make YSlow happy
Add the following to /etc/apache2/apache2.conf
Restart Apache to apply the changes
Test with YSlow and see the difference!
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