I am considering installing Parallels 11 on my iMac Retina and Macbook Pro Retina machines to run the MS Office Suite, Quicken, and a few other applications. I assume that the iMac won't see much impact from this activity (both machines are top-of-the-line machines), but I'm unclear on the impact to battery life on the Macbook. Does Parallels always run, meaning that it will drain my battery faster, even when I'm not running one of the Windows applications? Or will my battery drain faster only while I'm actively running one of the Windows applications? I don't mind having resources taken more quickly when I'm running programs, but I don't want to take a constant, significant hit to resources or battery life for the 95% of the time I won't be using a Windows program. Thanks for your insight.