But wouldn't you normally set it up in a failsafe configuration therefore you would power the solenoid to allow the beam to pass? No power = No beam emission
This would then have nothing to do with the operating speed of the circuit but more about the mechanical speed of the moving the shutter with no power applied.
And even if you had it configured in Non-failsafe configuration you would still need to consider the addition of both the speed of the circuit and the mechanical speed of the shutter to get the total latency, therefore the less time in the mechanics the lower the latency of the shutter in total.
Besides, for the typical hobbyist, what would the speed of the shutter need to be for safety?