When you click on an application in App Tamer's list of processes, a window like the one at right pops up. Choose one of the checkboxes to reduce the amount of CPU and battery power the app uses:
Stop this app completely
When you turn on this checkbox, App Tamer will pause the app whenever it's in the background. This saves the most power, but prohibits any activity in that application until you bring it to the front.
In web browsers like Safari, Firefox and Chrome, this means that animated ads will not play and websites like Facebook will not automatically refresh every few minutes. Applications like Twitter, Messages and Skype that sync with servers on the Internet won't do so until you bring them to the front.
Slow down this app if it uses more than [x]%
Turning on this checkbox prevents an application from using more than a certain amount of CPU time when it's in the background. App Tamer monitors the app's activity and slows it down if it starts to use more CPU than you've allowed for it. This will also reduce the amount of heat (and resulting fan noise) generated by your Mac and keep your machine more responsive, rather than letting it get bogged down with a lot of background activity.
This strategy will not save as much power as stopping an application completely, but will allow the app to do some work in the background at a reduced speed. It's useful for applications like Mail, Spotlight and Time Machine that you still want to work behind the scenes but don't want to impact the performance of other applications or quickly run down your battery.
Only stop or slow this app when it is hidden
This option is enabled when you choose to slow or stop an application, and does what it says it does. App Tamer will not slow or stop the application until you hide it (using the "Hide" or "Hide Others" command in the application menu).
How to pick a CPU percentage for slowing an application: Try 10% and see if the app still gets its background work done in a time you find acceptable. If it doesn't, give it a little more CPU. There could be a bit of experimentation necessary to find out what works for particular applications and workflows.
Handling "Script is not responding" or "Unresponsive page" warnings: If App Tamer stops some web browsers for too long (including Google Chrome and Firefox) the browser will put up a warning saying that a page or script isn't responding. In these cases it's best to slow them to 1% CPU rather than stopping them completely.
App Tamer will not stop or slow a web browser while it is downloading a file, nor will it stop iTunes while it is playing music or importing tracks from a CD.
To make sure that OS X has time to update necessary application data, App Tamer will periodically wake up stopped applications for a few seconds. (By default, it does this every 5 minutes - this can be changed in your App Tamer preferences).