The netgraph also displays the frame rate, as well as the ping, current traffic and such informations. Toggle it using the command net_graph X, with X being 0 to deactivate it and X being 1 to 5 to set graph's mode.
Note that the most modes are quite a strain on the CPU and tend to drop FPS, so use the text-only mode (3, I think) if you don't want that.