[Howto] Optimize Your Site With GZIP Compression and cache

[EW-Team]

Part 2
Add future Expires and Cache-Control headers

A first-time visitor to your page will make several HTTP requests to download all your sites files, but using the Expires and Cache-Control headers you make those files cacheable. This avoids unnecessary HTTP requests on subsequent page views.

To set your Expires headers add these lines to your .htaccess:

<ifModule mod_expires.c>
  ExpiresActive On
  ExpiresDefault "access plus 1 seconds"
  ExpiresByType text/html "access plus 1 seconds"
  ExpiresByType image/gif "access plus 2592000 seconds"
  ExpiresByType image/jpeg "access plus 2592000 seconds"
  ExpiresByType image/png "access plus 2592000 seconds"
  ExpiresByType text/css "access plus 604800 seconds"
  ExpiresByType text/javascript "access plus 216000 seconds"
  ExpiresByType application/x-javascript "access plus 216000 seconds"
</ifModule>

To set Cache-Control headers add:

<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)$">
    Header set Cache-Control "max-age=216000, private"
  </filesMatch>
  <filesMatch "\\.(xml|txt)$">
    Header set Cache-Control "max-age=216000, public, must-revalidate"
  </filesMatch>
  <filesMatch "\\.(html|htm|php)$">
    Header set Cache-Control "max-age=1, private, must-revalidate"
  </filesMatch>
</ifModule>

Now all your files must have the right headers and be cacheable except the CSS and JavaScript files processed by JSmart. This is because JSmart overrides the cache headers when gzipping these files.

To fix this you have to edit /jsmart/load.php file and change the block code

if (JSMART_CACHE_ENABLED) {
if (isset($headers['If-Modified-Since']) && $headers['If-Modified-Since'] == $mtimestr)
header_exit('304 Not Modified');

header("Last-Modified: " . $mtimestr);
header("Cache-Control: must-revalidate", false);
} else header_nocache();

TO

if (JSMART_CACHE_ENABLED) {
  if (isset($headers['If-Modified-Since']) && $headers['If-Modified-Since'] == $mtimestr)
    header_exit('304 Not Modified');
 
  if ($file_type=='js') {
    header("Expires: " . gmdate("D, d M Y H:i:s", $mtime + 216000) . " GMT");
    header("Cache-Control: max-age=216000, private, must-revalidate", true);
  } else {
    header("Expires: " . gmdate("D, d M Y H:i:s", $mtime + 604800) . " GMT");
    header("Cache-Control: max-age=604800, public, must-revalidate", true);
  }
} else header_nocache();

With these settings you should have your site a lot faster and your file?s size greatly reduced.

Resources
Some descriptions are based on .htaccess (Hypertext Access) Articles from AskApache.
mod_gzip settings are taken from Highub ? Web Development Blog.