Acrobat Reader has grown from a simple portable document reader to a behemoth. Most of the time you just want to view a PDF. You don't need all the features of Acrobat when you already have a perfectly good PDF reader in Preview.app.

1. Make Preview.app your default PDF viewing application. To do this find a .PDF file and use the Get Info command. Choose Preview from the "Open with" section. Then press the "Change All…" button. The next time you open a .PDF it should open in Preview.