Hi, i'm running a Bridge/iptables firewall, with no tc filters configured CPU utilization barely reaches 1%, i had to rate limit one particular server outgoing traffic and setup a HTB scheme like this

iptables -F PREROUTING -t mangle
iptables -A PREROUTING -t mangle -p tcp -s 99.99.99.99 -j MARK --set-mark 2
tc qdisc del dev eth0 root
tc qdisc add dev eth0 root handle 10: htb default 10
tc class add dev eth0 parent 10: classid 10:3 htb rate 1000kbit ceil 1000kbit
tc filter add dev eth0 parent 10: protocol ip prio 3 handle 2 fw classid 10:3

Now i'm seeing CPU Utilization beyond 30% and load averages of 0.79, the network total bandwidth is 20Mb/s.  The server is a linux kernel 2.6.7-gentoo-r8  running on a P4 1.7 Ghz.
Is this normal behaviour ? is there any error in my configuration or in my kernel config ?
Thanks!