I have an old standard USB charger for my BlackBerry PlayBook that is designed to charge the relatively large PlayBook battery fairly quickly and it REALLY speeds through a charge.
From my experience, using a standard USB cable with a USB plug-in adapter will ALWAY run slow. I believe that USB cable limits the power that can be delivered. In my car, I have a DC adapter that I plug in to the lighter and it has two options: one, is a hardwired connection to the adapter and the second is a USB slot for a separate USB cable. Using the hardwired cable allows the phone to charge MUCH faster than using the USB cable plugged into the slot. I would look for a hardwired charger for home and the car and you will be pleased.