Non-responsive/lagging editor when clicking in lower-right corner

Hi! I’m having a very strange issue with the editor that I can only recall getting after updating to 4.13. Whenever I’m selecting, clicking og dragging things from the lower-right corner of my screen, in a box that covers approximately 5-10% of the screen, the editor starts to lag/freeze, and is unresponsive to any selection I make within that area. I can’t drag some meshes into the scene or select stuff from the world outliner. Any help would be appreciated!

Including a screenshot visualizing the affected area.
EDIT: This is only happening in Unreal Editor, not in any other Win32 program.

Try closing the Epic launcher, it uses too much resources though that might not be the issue–might as well try it though.