[ale] iptables slowing down the website?

[Christopher Bergeron]

Does anyone know why the usage of iptables could slow down a webserver?

My website uses mysql, httpd, and dns.

My rules are similar to the following:

DROP all INPUT by default
let any output flow (OUTPUT ACCEPT)
INPUT from dns accepted (INPUT -p tcp -j ACCEPT)
INPUT from httpd accepted (INPUT -p tcp -j ACCEPT)
INPUT from mysql accepted (INPUT -p tcp -j ACCEPT)

I'm no iptables guru, but my rules make sense (at least to me).  Is 
there something that I'm missing?

Thanks in advance,
CB