It depends on the speed of your internet connection. Your first time downloading the game may take a little while, but updates after the first download are normally pretty quick.
We recommend all users begin to play directly in the web browser and are working towards retiring all installs in the near future. To play in the browser, you will simply need to log in at https://account.tytoonline.com/login and then press "Play the Game!" from the homepage or sidebar.