Is there anyone using RB450. I am taking 4 WAN loadbalancing aswell as controlling bandwidth through simple Queueing but facing slow browsing although my Resources are not being used more than 10 percent. Can anyone help?

Read and watch these two presentations.

Load Balancing Using RouterOS and PCC by Steve Discher:
PDF
Video

Bandwidth-based load-balancing with failover - the easy way by Tomas Kirnak:
PDF
Video