If you want to win the case, you must NOT focus on the performance issue. Like I said before, the reason you were let go was not your performance and the company never said your performance was not good.
At the time you accepted the job offer, you must sign a contract. Inside it has a sentence or in your employee handbook, says something like "voluentery basis". (I don't remember exactly the sentence) It means you can leave the company at any time you want, and the company can let you go too. Therefore, the company can always say your position is no longer needed. Even it hires a new person, the company can always give it a different title. Therefore, PLEASE DO NOT FOCUS ON "PERFORMANCE", YOU WILL NOT WIN IF YOU DO THAT. You have to find something like discrimination or verbal abuse by your boss, you have a much stronger case and better chance to win.
