Battery Optimization?

I'm using Parallels on my desktop and it works great, however, on my Air, I've noticed that Battery life takes a nose dive. I basically want access to Outlook and IE through windows and was wondering what would be the optimal configuration so that the drain on the battery is as little as possible.

 

When you run Parallels Desktop, additional CPU load occurs, thus battery is serving less time

 

Sure- I can understand that. But I generally go down from getting about 4 hours on my MBA to about 2 hours and 20 minutes. Thats a LOT of difference and I was wondering if there is a way to minimize that.

 

I am afraid no way, unless you want to pause VM, where you are not using it