It DOES charge slow...but 4% seems outrageous. Mine goes about 25% per hour. One thing you might want to take note of. The battery is fine with video, music, apps, and light net browsing. But it doesn't hold up well to repeated loading and posting at message board/forums. That can drain the battery fast, so I'd use your cellphone browser to read and post at message boards like this.
If I dont want to run the battery down too quick, to 30% or so, I'll shut the internet down on the Note 10.1, turn the cell net on and browse forums. The cell (Nexus) gets a full recharge in only 35 minutes, so its no big deal draining that.
Oops, I almost forgot to tell you...leaving your internet connection on while recharging can make the recharge slower. Turn the net connection, be it WIFI or 4G, off in the settings. Might want to use the task manager to turn off all the apps too.