What effect does switching frequency have on a switching booster circuit?
In general, in both boost and buck switching regulators, a higher switching frequency allows the use of physically smaller inductors and capacitors. However, a high switching frequency can also eat into the overall efficiency of the regulator, through switching losses both in the switch itself and in the gate-drive circuit.

Yes, the diode contributes something to switching losses, too, but that can be mitigated by using synchronous rectification; i.e., replacing the diode with another MOSFET. (But then, that MOSFET has gate-drive losses, too ... as you can see, optimizing one of these designs can involve a surprising number of tradeoffs.)