USB 3.0 drive in 2.0 port - 1 or 2 plug cable?

I just received my Element SE 1TB today which is of course a USB 3.0 drive, seems to be great so far but I was wondering about the cable. The USB 2.0 drives used to come with those two plug cables if more power was needed, so it occurred to me this may be needed if you use this drive with USB 2.0 ports too, but of course the end that connects to the drive itself has that new flat type connection.

So will there be some scenarios where this is needed? Also it seems like external HD can sometimes work but perform slower with USB 2.0, would this be the case sometimes if I use this drive in a USB 2.0 port?

The old micro USB cables are also compatible with the passport USB 3.0, but you will only get USB 2.0 speeds. But unless you notice any stability problems you don’t need a power booster cable.