microUSB charging problems

A. No, microUSB is isn't the culprit here. I'll lay odds that you're either using a mains charger from a previous Nokia phone or charging from a microUSB data cable. In both cases, you're hugely limited in terms of current. You'll remember that Nokia do write in their booklets that 'you should always use the charger supplied with the phone'. For optimum results, at least.

You see, the output current does vary quite considerably, from 300mA in Nokia's travel (and small phone) chargers to 1200mA for the hungriest smartphones. And current from a data cable is dramatically lower again, typically 100mA - data cable charging should only ever be thought of as trickle charging ('topping up') a device.

Unplug your charger from the wall and look at the small print on it, under 'output'. For a decent charging time on a recent S60 smartphone you need an Amp or more. Nokia's AC-10 range has a power output rating of 1200mA, i.e. 1.2 Amps, for example. So, upgrade/switch your wall charger and you'll be charging much, much faster!