My girlfriend's 2011 MBP keeps wifi connections even when you shut the lid. When the computer is re-opened, the computer is ready to go. Wifi is connected, no delays. However, on my 2010 MBA, and my 2012 MBP, when I open the comp and raise the lid, I have to wait for the computer to re-connect to wifi, and there's usually a delay while the clock catches up and the comp "wakes up." Any suggestions? I figure it's gotta be something in power settings but I know my MBA is set to not "Put hard disks to sleep when possible."