When I play BF4 and alt-tab out, it auto-tabs back in to the game and it's annoying. I hate when I get a friend notification and the window minimizes too. How do I stop it from doing that??

Set your game video to "Borderless," and not "Full"  

I tried that and it made the game feel smoother but then I would get graphic lag that wouldnt happen before, so I went back to full screen mode. Is there a way to get this to stop happening in full screen mode?

Make sure your video resolution is set to the "recommended" or "native".  For example, my 27" Samsung is 1920x1080. 

Sucks to be you? :banana:

Well I just lowered the performance settings in Windows 7 (Right Click Computer -> Properties -> Advanced System Settings -> Advanced Tab -> Perfomance Settings -> Adjust for best performance)  and it didn't do it once today when I received friends notifications and I'm still running in Full Screen mode. I sure hope it fixed it!

Solution=upgrade from emachine. 

Under settings go to Notifications and uncheck the show notifications, just check the 'play sound' so you know when friends go on or off. That way the little window wont pop up and minimize your game. I had that same problem.