[AuckLUG] iptables, custom chains is the speed worth it?

[Robert]

I like to keep it simple where possible so don't usually worry with 
custom iptables chains and just use the defaults I find it easier to 
read that way and follow an iptables script.

I know however that if you have custom chains you can cut down on the 
processing the firewall has to do for each packet so my question is if 
your not using custom chains how many rules would you need before packet 
speed is affected or the system starts bogging down from the complex 
path to traverse?

Robert