When "PrecisionXServer" or "PXSW10_x64" are running they severely reduce the fps of Unity3D(the engine itself, not games made with it). This is a old issue as you can see here:
forum.unity3d.com/threads/unity-editor-and-precisionx-editor-renderered-useless-because-of-fps-lag.348949/
Also for some reason I can't use real links, they get deleted from my message.