One of the grand new features in OS X Mavericks is App Nap, which saves on power to extend battery life on MacBooks. One of the unfortunate side effects is that is kills background rendering in Final Cut Pro X and other apps that take advantage of background rendering.
To make background rendering work again, simply turn off App Nap. The process is simple.
- Right-click on the application.
- Choose Get Info.
- Check the box “Prevent App Nap.”
- Enjoy background rendering again.