The biggest power hog inside a smartphone is the GPS chip. This component can take 30 seconds just to acquire the satellite data necessary to get the information it needs for an initial location fix; it then has to churn through the downloaded codes to calculate its location precisely.

Microsoft researchers reduced that power consumption dramatically by offloading some of the work to the cloud.

via A Microsoft Research Project Offloads GPS Data and Calculations to the Cloud to Save Battery Life. | MIT Technology Review.