Here's something kind of fun that demonstrates the influence of sail setting and relative wind direction on the speed of a typical fore-and-aft rigged boat: http://www.thepirateking.com/ships/sail_simulator.htm
I am certain it's not super accurate but it gives a reasonable approximation of how fore-and-aft rigged boats perform. Quite different than square riggers, which are optimized for broad reaches if I'm not mistaken.