Tesla handling fundamentals
Here is my advice based on experience with the Roadster and track driving in general:
In comparing the Tesla Roadster or Roadster Sport to other sports cars there are some basic fundamentals that define the handling characteristics of the Tesla that trace their roots back to a single thing: the Tesla is based on one of the most finely tuned/balanced chassis in the world but then adds about 800 pounds toward the back.
As a result, you have a few things that you really can't get around.
1) The brakes, which are the same as the Elise/Exige, were designed to stop a car that was 30% lighter. As a result you will have a harder time stopping in high-speed stuff and the brakes will fade more etc. etc.
One might then conclude that the best after market mod would be a big brake kit for the Roadster, but there are some problems with this: most importantly, braking is ultimately limited by the traction available in your front tires, and the front tires are very narrow. In the case of the porsche comparo, the Roadster Sport has 195mm wide tires and the Porsche's are 20% wider at 235. The problem is worse if you don't have the sports package and your front tires are 175mm wide. Bigger brakes certainly wont help with the standard setup. They might do something with the added grip of the 195mm AO48s (I never drove that particular setup) but the other problem is that the front wheels of the Tesla are 16" in diameter so there isn't much room for bigger rotors/calipers.
2) The lack of grip/contact patch in the front, combined with the weight in the rear, leads to a significant tendency to understeer (and the oversteer) in various situations. This is directly related to the above paragraph, and the only thing you can do about the understeer is put the wider, grippier AO48s up front, use the adjustable swaybars to tune out the understeer (I believe you should use the softer setting up front and stiffer in the rear but you should consult a tuner familiar with lotus chassis), and use camber adjusters. Camber shouldn't mess with efficiency (toe does) but dialing in camber will cause more wear in the inside track of the tire under normal driving which may cause you to replace the tires more frequently. Once you get the understeer under control be careful about oversteer!
Still, all of these tweaks will help things but they cant overcome the basic imbalance of car's setup. The Tesla will not handle as well as top sports cars but will try to make it up with the great acceleration.
Still, I would strongly recommend that anyone who likes to drive aggressively on the streets or on twisties (like Dr. Taras) should upgrade to the sports suspension and run the wider AO48s. The standard roadster is a bit scary at the limits!
(PS - the other reason the Tesla will not shellac ICE sportscars on racetrack comparos is that acceleration drops off notably after 60/70 mph. So the more long sections of the track, the more the Tesla will be at a disadvantage. Tesla's should compare well at tracks like Infineon but compare more poorly at fast tracks like Laguna Seca. The undersized brakes will compound this problem)