UE4 is extremely laggy

I have just recently started using UE4, and there is a big problem when running the application: the editor and gameplay is extremely laggy. It’s like the engine is behind on where my cursor is, if that makes sense. The weird thing is whenever I click a drop-down box, everything works smoothly: the animations run at constant 60fps, and the engine follows my cursor correctly, but once I exit the drop-down box, everything slows down again.

I have googled this for a while and I cannot find a solution that works for me. I tried lowering the Engine Scaling, but that didn’t work. I even checked the recommended specs, and I meet those requirements.

SPECS:

Processor: Intel QuadCore i3-4130 3.4 GHz

Memory: 8GB

Windows 8 64-bit

DirectX 11

EDIT: I disabled Motion Blur and that solved the lag in the game, but the editor hasn’t changed.