PII fast enough for firewall

[John Schmidt <john.andrew.schmidt@gmail.com>]

Hi,

I have a 15K Mbs connection (up/down) to my house (fiber to the home).

I have a Buffalo router that connects to my WAN and then one of the LAN ports 
on this router connects to my IPCOP firewall that is running on a PII -- 400 
MHz box with 64 MB of RAM.

When I do a speed test from my box behind my IPCOP firewall, I get about 10K 
Mbs up/down.  

If I move the connection to one of the Buffalo router LAN connections, I get 
the advertised 15K Mbs up/down speed.

So routing traffic thru the IPCOP firewall slows things down quite a bit.  Is 
this to be expected?  I was thinking of changing the firewall to a debian box 
running shorewall, and was wondering if I could tweak the firewall/router to 
not slow things down appreciably like the ipcop box is doing.

Thanks,

John Schmidt