Enabling zlib compression makes a huge difference to a http server. I stress tested this server using Apache Bench. Before compression was enabled I managed just over 1-2 requests of (large) pages per second, but with compression that rose to 10 requests per second! Just add this to a .htaccess file if you’re using PHP 4.
php_flag zlib.output_compression On
Update – Enabling compression that way here causes too many problems. I’ll have to try and convince Colm to install mod_gzip which works everywhere else I’ve used it.