Launch Game bad performance

Hello,

What exactly causes a Launch Game “Right Click Launch Desktop UE4 Icon” to launch a more heavier version of the game?

When I play the game in the Editor it runs extremely well and when I launch the game and play it on its own FullScreen window it plays twice as worse.

How can you fix this?

Your actually launching the game. If you look in your project you will more than likely find an exe. Try play in new window, and enlarge it.