optimize apache for speed (in ubuntu)
I usually compile/enable only the very basic modules for apache (httpd core and php)
but if you have an production sever you can check and disable modules that are not used
You can find them by looking in the server-info area in apache (http://localhost/server-info)

Here is the basic list that is left after cutting the fat :

mod_php4, mod_ssl, mod_so, mod_auth, mod_access, mod_rewrite, mod_alias, mod_cgi, mod_dir, mod_autoindex, mod_include, mod_info, mod_status, mod_mime, mod_mime_magic, mod_log_config, mod_vhost_alias, http_core

If there is more need for speed you can cut more

and use only http_core,mod_php4,mod_mime, mod_mime_magic, mod_log_config,mod_vhost_alias,mod_ssl
basically you reduce the apache to an small core similar to lighttp web server.

ps: i like the list of sites powered by lighttp
who the hack are u2bes ?