So it's time to measure how it behaves on electrical side of things:

First the efficiency, it depends on the current of course and the power supply voltage. It's pretty good, over 90 % for currents higher than 0,5 A for the whole power supply voltage. The efficiency is topping at 96,9 %!

The frequency side is similar, the buck driver frequency depends on the voltage difference and absolute value of input voltage, from almost 250 kHz it drops to 0 when voltage difference between led and power supply is under 100 mV:

The current through LED looks like:

And the voltage in switching point (where diode, transistor and coil are connected together):