If you're going to spend money on an adapter, I'd recommend installing a 6-20 outlet and changing the circuit to be 240V circuit. Then, all you'll need is the 6-20 adapter from Tesla, and you'll be charging at 15mph. Of course, it might take a while for the adapter to ship from Tesla, but at least it's faster than the 120V charging.
Note: I currently have a 6-20 charging setup that I installed for our plug-in XC90, as it is the max it can charge at. I use the charging cable from the XC90 plus the J1772 adapter for the 3. It's been fine, but I'm looking to add an additional 6-20 outlet so I don't have to swap back and forth each night, and it will allow both cars to charge at once (garage is limited to 40A).
Note: I currently have a 6-20 charging setup that I installed for our plug-in XC90, as it is the max it can charge at. I use the charging cable from the XC90 plus the J1772 adapter for the 3. It's been fine, but I'm looking to add an additional 6-20 outlet so I don't have to swap back and forth each night, and it will allow both cars to charge at once (garage is limited to 40A).