You need to describe your throughput testing methodology, to fully utilize pcc you need many connections, with good traffic distribution between them (something like very popular torrent download). Also make sure that your setup is as close as possible to example given in manual:
http://wiki.mikrotik.com/wiki/PCC#Appli ... _Balancing
I have this rb450G configured like this
IP FIREWALL
add action=accept chain=prerouting disabled=no dst-address=10.10.10.0/24 in-interface=LAN
add action=accept chain=prerouting disabled=no dst-address=10.10.20.0/24 in-interface=LAN
add action=accept chain=prerouting disabled=no dst-address=10.10.30.0/24 in-interface=LAN
add action=mark-connection chain=prerouting disabled=no in-interface=LINE1 new-connection-mark=wan1_conn passthrough=yes
add action=mark-connection chain=prerouting disabled=no in-interface=LINE2 new-connection-mark=wan2_conn passthrough=yes
add action=mark-connection chain=prerouting disabled=no in-interface=LINE3 new-connection-mark=wan3_conn passthrough=yes
add action=mark-connection chain=prerouting disabled=no dst-address-type=!local in-interface=LAN new-connection-mark=wan1_conn passthrough=yes per-connection-classifier=both-addresses:3/0
add action=mark-connection chain=prerouting disabled=no dst-address-type=!local in-interface=LAN new-connection-mark=wan2_conn passthrough=yes per-connection-classifier=both-addresses:3/1
add action=mark-connection chain=prerouting disabled=no dst-address-type=!local in-interface=LAN new-connection-mark=wan3_conn passthrough=yes per-connection-classifier=both-addresses:3/2
add action=mark-routing chain=prerouting connection-mark=wan1_conn disabled=no in-interface=LAN new-routing-mark=to_wan1 passthrough=yes
add action=mark-routing chain=prerouting connection-mark=wan2_conn disabled=no in-interface=LAN new-routing-mark=to_wan2 passthrough=yes
add action=mark-routing chain=prerouting connection-mark=wan3_conn disabled=no in-interface=LAN new-routing-mark=to_wan3 passthrough=yes
add action=mark-routing chain=output connection-mark=wan1_conn disabled=no new-routing-mark=to_wan1 passthrough=yes
add action=mark-routing chain=output connection-mark=wan2_conn disabled=no new-routing-mark=to_wan2 passthrough=yes
add action=mark-routing chain=output connection-mark=wan3_conn disabled=no new-routing-mark=to_wan3 passthrough=yes
IP ROUTE
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=10.10.10.1 routing-mark=to_wan1 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=10.10.20.1 routing-mark=to_wan2 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=10.10.30.1 routing-mark=to_wan3 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=1 dst-address=0.0.0.0/0 gateway=10.10.10.1 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=2 dst-address=0.0.0.0/0 gateway=10.10.20.1 scope=30 target-scope=10
add check-gateway=ping disabled=no distance=3 dst-address=0.0.0.0/0 gateway=10.10.30.1 scope=30 target-scope=10
i dont have other rules.
before i was with two lines 30/10 Mb and router go to 55-58 cpu load 50%
now i put the third one 30/10 cpu 65% and the router cant go more than that.
i am waiting for the cloud router but it takes 2 weeks to arrive here in my country
and the clients are really bored.
if the problem is the rb450g i know i have to wait, but if not i have to get a solution