Perhaps if Mr Nate defines what he means by "improved perfromance" then people can give better advice. Do you want outright speed, or more grip around corners, or more slide, or more brakes and acceleration, or more stability, or what? What exactly does not work 100% right for you with this slotcar?
All this talk of gluing everything down as a solution to every slotcar issue makes me wonder if at least 50% of slotcar fanatics are secret habitual gluesniffers
You don't have to glue anything unless NSR have stopped fitting their cars with adjustment screws. In all their models there are screws to tighten any movement down. And you certainly don't need to glue the motor in as NSR do a supertight fit with their motor/pod.
More important is that you leave a tiny movement in the rear so the car is almost rigid but not solid. A little rear 'suspension' wobble help to speed around corners when you have tremendous NSR tyre grip. But too much bouncy suspension destablises a lot of slotcar models.
The first thing I'd do is pull out the heavy rear-end longcan KING motor and fit a smaller and lighter shortcan Shark motor with the same g/cm and rpm. That'll reduce all the weight in the back while creating a more stable and faster speed around corners without the bum-heavy motor pulling the rear-end out. The lost weight can then be distributed with a little lead ballast to give a better centre of gravity in the middle of the car, or closer to the front. Or if you use magnets, then you won't need any extra weight at all.