Expire and header mods Apache rules to improve cache on statics files. Apply 864000 seconds cache on images, icons, html, javascript and css files. To insert in apache Virtualhost.

site.xml

<IfModule mod_expires.c>
    ExpiresActive On
    ExpiresDefault "access plus 180 seconds"
    AddType image/x-icon .ico
    AddType text/css .less
    ExpiresByType image/jpg "access plus 864000 seconds"
    ExpiresByType image/jpeg "access plus 864000 seconds"
    ExpiresByType image/png "access plus 864000 seconds"
    ExpiresByType image/gif "access plus 864000 seconds"
    ExpiresByType image/ico "access plus 864000 seconds"
    ExpiresByType image/icon "access plus 864000 seconds"
    ExpiresByType image/x-icon "access plus 864000 seconds"
    ExpiresByType text/css "access plus 864000 seconds"
    ExpiresByType text/javascript "access plus 864000 seconds"
    ExpiresByType text/html "access plus 60 seconds"
    ExpiresByType application/xhtml+xml "access plus 864000 seconds"
</IfModule>

<IfModule mod_headers.c>
    <FilesMatch "\\.(ico|jpe?g|png|gif|swf|css|gz)$">
        Header set Cache-Control "max-age=864000, public"
    </FilesMatch>
    <FilesMatch "\\.(js)$">
        Header set Cache-Control "max-age=2592000, private"
    </FilesMatch>
    <FilesMatch "\.(pl|php|cgi|spl|scgi|fcgi)$">
        Header unset Cache-Control
    </FilesMatch>
</IfModule>