Tic Tac Toe Feedback Please

I would really love some feedback for this Tic Tac Toe Game.
The main feature I worked on is a best decision making computer player.
The main issue is that it takes the computer (on my computer’s chrome) 9 secs to take the first move, even though I have optimized the algorithem a bit.
Here is the Github repository: https://github.com/carpben/TicTacToe . Keep in mind that my JS is in script2.js: https://github.com/carpben/TicTacToe/blob/master/script2.js .


I optimized the getBestMove function, so now it only takes 2 secs for the computer to take the first move on my Google Chrome.