MOSFET switching speed
What you are seeing has little to do with the capacitances you mention. Instead, you are seeing the effect of large drain-source capacitance. This has little effect on turn-on performance, but determines the turn-off speed. 

When the gate voltage drops to zero, the drain voltage will rise (approximately) as a simple RC circuit using the Coss and the drain resistance. For the IRLZ34, Coss is nominally 660 pf. So a 330 ohm drain resistor will produce a time constant of about 200 nsec, and 400 nsec is two time constants. 3k produces a time constant of about 2 usec, and 47k gives 31 usec. With no detailed responses provided by you, it seems pretty clear that these numbers are an OK match for what you seem to be seeing. The actual capacitances would seem to be a bit smaller than the data sheet numbers, but that's not unusual.

The effective capacitances involved are actually voltage-dependent, so the results are not as simple as might be wished, but this approximation to the real results seems to give reasonably close answers.