I have been reading through the yahooui speed/performace blogs recently and started implementing browser side cache, gzip etc...
Some of this does the same as the PHP headers but this htaccess prevents images from flickering.
Basics of how it works is when it sends a request to the browser it receives a 304 Not Modified rather than a 200 OK which results in the browser downloading the file again.
Also enabling gzip will hugely compress html, css, javascript to increase loading times.
AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript
<ifModule mod_expires.c>
ExpiresActive On
ExpiresDefault "access plus 3600 seconds"
ExpiresByType text/html "access plus 3600 seconds"
ExpiresByType image/gif "access plus 604800 seconds"
ExpiresByType image/jpeg "access plus 604800 seconds"
ExpiresByType image/png "access plus 604800 seconds"
ExpiresByType text/css "access plus 604800 seconds"
ExpiresByType text/javascript "access plus 604800 seconds"
ExpiresByType application/x-javascript "access plus 604800 seconds"
</ifModule>
<ifModule mod_headers.c>
<filesMatch "\\.(ico|pdf|flv|jpg|jpeg|png|gif|swf)$">
Header set Cache-Control "max-age=2592000, public"
</filesMatch>
<filesMatch "\\.(css)$">
Header set Cache-Control "max-age=604800, public"
</filesMatch>
<filesMatch "\\.(js)$">
Header set Cache-Control "max-age=604800, private"
</filesMatch>
<filesMatch "\\.(xml|txt)$">
Header set Cache-Control "max-age=216000, public, must-revalidate"
</filesMatch>
<filesMatch "\\.(html|htm|php)$">
Header set Cache-Control "max-age=3600, private, must-revalidate"
</filesMatch>
</ifModule>
FileETag MTime Size
