Visual Studio because of Unreal Engine 4. It is an IDE for developers, or, to be precise, a glorified text editor.

How do you fuck up a text editor? You ask M$ to write it. It manages to hog my entire system periodically, and we are not talking about just any system. We are talking about a game dev's machine.

It is slow, it sometimes doesn't even open when you tell it to without any logical reason, and it's full of redundant information and options everywhere. They should force Bill Gates to use this crap 12 hours a day so he can understand what it's like to wait 30 seconds for what amounts to a glorified text editor to respond to each keystroke.