I echo BackAlley’s call for oil or some kind of cutting fluid. It helps keep the cutting edges cool and sharp. WD40 works pretty well and is easy to apply right on the spot using the little straw it comes with. Higher rpms is just going to heat up your bit with friction and melt your cutting edges. Switch your cordless to it’s lowest speed which is highest torque, put on a little pressure, spray some cutting fluid…it’s still going to take a while.
Dailydawg’s right though, make that hole however you can. Heck why not just shoot a hole in it!