The 10k resistor helps the MOSFET to turn off faster than it would without it by giving a discharge path to the gate capacitor. Actually that value appears to be a bit too high...but that depends on the gate capacitance and/or the voltage that it charges up to. Higher values need lower resistance for discharge to happen quickly. However too low a value might limit the voltage available to charge the gate capacitor especially if there is a current limit resistor present by voltage divider action. So turn on time will be affected.