The performance documents from Cisco say that the 3825 is capable of 350,000 packets per second for a rate of 179Mbps. I know that they are using small packets to establish this. What throughput can I really expect?
The 3825 configured for only IP can push around 1Gbps, or 400k PPS. This is based on a mix of small and large packets, representing typical internet traffic.
With services turned on (qos, firewall, vpn, nat, nbar), expect to see anywhere between 100-300Mbps throughput, depending on which service it is, and what combination of services are configured.