The normal R1 value would be between 10 and 50 Ohms. Using a high value like shown will slow down the charging of the gate. A mosfet gate is a form of capacitance, so the faster you can charge it the faster the mosfet turns on. Putting a high value resistor in the cicuit like your R1, slows down the time to charge the gate. The problem with that is the slower the mosfet turns on the longer it stays in a region of operation the cause the mosfet to heat up, called the "ohmic region", where the mosfet is more resistive. When the mosfet is fully on this region of operation is much less.