My Number one tip to people who alt + tab* a lot whilst playing is to play in “Full Screen Windowed” mode.
To do this press escape > Options > Display: Full Screen Windowed.What is the difference? From Microsoft: Full-screen mode means the window that the application runs in covers the entire desktop, hiding all running applications. Games typically default to full-screen mode to fully immerse the user in the game by hiding all running applications. An application running in windowed-mode shares the desktop with all running applications.
What does this mean to me? By selecting Full Screen windowed you still get to play the game in full resolution (some people even find it faster as well) however when you want to alt + tab out (to go check WowHead, Thottbot or just Facebook) the computer doesn’t have to reallocate all of it’s resources so this is instantaneous and seamless allowing you to pop in and out of the game at a whim.
Once I discovered this tiny quality of life change I was so happy – hopefully you will be too!
*Alt + Tab is a way to switch between programs quickly. If you press Alt + Tab once you go to your previous program, by holding Alt and then pressing tab you get a mini box showing which program you are selecting. If you are on windows 7 the windows key + tab does a similar job but flashier!