If your server is running Apache 2.xx then mod_deflate can be used to compress certain file types, which will give a real boost in loading speed as the client’s browser will be uncompressing the content, rather than the server carrying the full load.
To enable mod_deflate, add the following to root htaccess (or ideally http.conf or if on a virtual server, vhosts.conf)
If your server is running Apache 1.x then mod_gzip can be used. This can be added to the root htaccess file.
You might also like to enable Gzip Compression through Admin/Configuration/Gzip Compression, set at 9.