Performance issues when enabling netfilter configuration

[Raviv <raviv.haim@gmail.com>]

Hi,

I'm developing a bridge application (Ethernet <--> wireless) for both AP 
and Station.
I would like to keep a single kernel image for both AP and station. 
However the netfilter capabilities (conntrack) are only required at the 
Station.
I have configured the required netfilter capabilities to be loaded as 
modules. still there are some basic configurations i can't set as 
modules but only as built-ins.
So even-though i don't really need the netfilter in the AP these basic 
configuration exists and causes performance issue for network traffic 
(15% desegregation).
After a brief debug session i found out that when running the system 
without netfilter the packet (travailing : Eth-->Bridge-->Wireless) is 
passed with the same skb (all the way), while when netfilter is on the 
packet has a different skb while in Eth driver then the skb in the 
wireless driver. I suspect the skb switch/copy has happened in the 
bridge code.

1. Is there a way to maintain a single kernel image without hurting the 
performance so bad?
2. Why is the packet copied from one skb to another?

Regards,
Raviv