As far as I know, PS/2 keyboards are interrupt driven, while USB are polled. Typically a PS/2 keyboard was assigned IRQ_1 on Windows.

I'm no hardware expert, but at a first glance seems like the PS/2 keyboards are more efficient. So here are my questions:

1. On modern day computers, are PS/2 keyboard better (or faster), and if so, would it be noticeable at all? (e.g.: in gaming)
2. Since they don't need polling, do PS/2 keyboards save energy compared to USB? (notice I'm not talking only about the peripheral here, but about the overall computer energy consumption).
3. In case PS/2 had any advantage over USB, would adding a PS/2 adapter to my USB keyboard make the device as good as an actual PS/2 keyboard? Conversely, would adding a USB adapter to a PS/2 make it as bad as a USB KB?

Thanks in advance.