Hello,
It depends what you mean by performance... For power / torque figures, performance upgrades are a bit thin on the ground unless you are happy and familiar with breaking in to and noodling around with embedded Linux machines and vehicular network protocols - see posts from the inimitable wk057 for more info.
That aside, like any car, you can modify and/or upgrade wheels, tyres, brakes, aero etc, but that may not be what you're looking for. Nothing to say you couldn't re-gear the transmission to reduce top speed but increase torque, but technically that doesn't give you any more power - it just redistributes they dynamics of what you already have.
Tesla at present hold the vast majority of the cards when it comes to upgrades, and they are presently unwilling to consider such things. As I understand it, theoretically it is possible for you to remove your 350-volt 60 pack and replace it with a 400-volt (85/90/100 kWh) pack to get more range and more power for the same current out of your non-P RWD motor, but I am unaware of anyone doing so (yet). It may also be possible to noodle with the car's config and go down the uncorking route, but again that's way off-book as (again AFAIK) only the newer 75kWh packs with appropriately upgraded main contactors are capable of supplying sufficient current for a meaningful upgrade, so tricking the software into allowing more current may end, uh, badly... Or melty. Or burny :-D
