I can't remember where the other thread about this is, but I resolved it by making sure that my ac charger (the part that fits in the wall) was the same voltage, wattage, amperage, etc as the distribution charger, and that the USB cable was nice and thick (and that includes any USB cable extender you may be using). In my experience, you don't have to use the ones that came with the S3, but you have to use ones with the same specs. My problem is that I was using a skinny USB extension cable with the proper sized charger and USB cable. Once, however, I managed to use a wimpy charger with thick cables and everything was painfully slow.
Sent from my GT-I9300