Slew Rate controlled MOSFET switch
This part has great specs for RDS(on) and current (80 amps) but you pay somewhere, and here you have extremely high input capacitance and reverse transfer capacitance.  To speed up you will need a lower capacitance part (or more current) to overcome these capacitances when you hit the switching point.

You don't really need R1, but when it is there it limits the gate current.  Since you need to pull the gate down to 9 volts to switch and the VCE on the 2n2222 needs to be at least a volt or so, the 1.024 k resistor limits the mirror current to 8 ma no matter what is on the drive side.