Reducing CPU load (On an RB493G)

I have a series of RB493G routers, all the ports are active and they are just routing and using OSPF.

I want to run them as a fast as possible. I have disabled connection tracking and use hardware queues only.

Are there any other ways to reduce CPU utilization?

Ethernet, Networking and Unclassified use most of the cpu, we are trying to eventually support over 500mbit/s through the routers if possible.

They need to route as we use these in a ring with OSPF.

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