Unity pauses when tabbing out!

It seems that when I tab out of unity is pauses. So if i had unity to one side of my screen and something else on the other unity would be frozen until I click on it! Now I thought this would not be a problem but when I test out my game (Its a multiplayer game) when I switch between the editor and the game it seems that the player freezes where he is. To make it simple to understand, I have the editor on one side of my screen and the the exported version on the other. I run a server on the editor and the exported client joins when the export client joins I switch to the editor but it seems that the exported client stays froozen until i go back to the exported client. So can someone tell me if there's a way of stopping unity from pausing/freezing when i don't have it selected!