With switches all the packet forwarding is done by the silicon. The CPU and memory are used by things like dynamic routing protocol updates, spanning tree calculations, and the like.
Unless you have at least 10,000 layer 3 routes in your network you probably don't have to worry about CPU or memory.
Throughput can be gauaged from the Network-Wide/Clients view. If you are only using the Gigabit ports, then your maximum throughout would be 2 x 24 Gb/s, or 48Gb/s. So if you don't see the graph getting close to this you don't have an issue.
And even then, you could then consider using the 10Gbe ports for high traffic generators/sinks.