The electrical code calls for items plugged in for extended time frames to not exceed 80% of the listed circuit size, so on a 15A circuit, the max you could use would be 12A. Depending on the model year and the OEM EVSE, it is no bigger than that 12A (later ones, I've heard, are 10A), so on a dedicated 15A or 20A circuit, you could set the car's charging rate to maximum without issues. That all assumes that there is nothing else on the circuit (the reason the restrictions are there in the first place), but also, as a receptacle ages, the spring tension reduces, and that acts like a resistor (think heating coil), and things can overheat, making things worse, potentially melting the plug and receptacle.
Check to see if the plug gets hot. It could easily get warm, but should not get hot. If the plug slides in easily, you should replace the receptacle before things burn.
2011 535i x-drive GT, 2014 i3 BEV