apache2 performance on 5.3 SMP machine

[Jeff Behl]

howdy,

i'm running the latest apache2, compiled from the ports collection 
(apache-2.0.52_2; prefork), on a dual 2gHz AMD64 box from ibm.  the 
performance is very bad, with ~ %20 cpu at only ~115 req/s.   for 
whatever reason, almost all of the %20 cpu time is spent in system:

CPU states:  0.4% user,  0.0% nice, 17.3% system,  1.3% interrupt, 81.0% 
idle

is there a known problem that could lead to this?  i'm a bsd bigot, and 
after going mad with the IO lockup issues in the kernel that RedHat uses 
in their AES line (it's truely abysmal), I'd be overjoyed to move 
everything to BSD, but the redhat boxes on the same hardware aren't even 
breaking a sweat under the same load.  what i'd guess to be the most 
relevant pieces of hardware that could lead to high system load, the NIC 
and  hard disk controller, are as follows:

bge0: <Broadcom BCM5704C Dual Gigabit Ethernet, ASIC rev. 0x2003> mem 
0xfe000000-0xfe00ffff,0xfe010000-0xfe01ffff irq 24 at device 1.0 on pci2

mpt0: <LSILogic 1030 Ultra4 Adapter> port 0x3000-0x30ff mem 
0xfe040000-0xfe04ffff,0xfe050000-0xfe05ffff irq 26 at device 2.0 on pci2

apache config is:

<IfModule prefork.c>
ServerLimit       3000
StartServers        100
MinSpareServers    100
MaxSpareServers    500
MaxClients        3000
MaxRequestsPerChild  0
</IfModule>

is this a 5.3 issue in general, or specific to the AMD line?  any help 
or tips greatly appreciated.