How do I manually throttle the CPU usage of an app? When I export a file from iMovie, it usually takes a long time but uses a lot of CPU, and my computer gets very hot(around 180-190ºF), even with my fan controller maxing it out. Would I be able to slow this down so that it wouldn't put as much load on my computer? Or really for any app where it might be doing some intensive thing in the background. I get a little nervous having it working so hard for such a long period of time. I was hoping there would be some terminal command or other local way to do this,  Thanks. 

A1342 MacBook, Late 2009, 10.10.5, 4GB RAM
You could try AppTamer (not free, trial version available). From the AppTamer website:


  Some applications, particularly web browsers and older apps, continue 
  running tasks or animating ads even when they're idle. That uses
  valuable processing (CPU) power, which leaves you with:
  
  Less CPU power for the application you're using, Increased heat and fan
  noise, Reduced battery run-time
  
  Find the culprits and get them under control. With App Tamer, you
  simply do this:
  
  Launch App Tamer and click on its icon in your    menubar, Click on an
  application that's    using a lot of CPU, Tell App Tamer to slow or stop
  the app.