This is one of the items that is tested in your Windows 8 App when you use the WACK.
If you are in Southern California, please email this post for more information on getting a token for your app by June 30, 2012!
Respects allotted timeslots assigned by background tasks
Apps that run in the background or under lock screen receive a certain amount of CPU time at regular intervals. If the app uses all of its available CPU time, its background tasks are suspended until the app’s CPU quota is replenished at the next generation for CPU quota updates.
Budget your allotted CPU time to maximize continuity.