Something I noticed right now - I got freezes to become less frequent after doing nothing but simply navigating around and turning on that option.
Then I tweaked materials and replaced old materials on some meshes - bam! freeze after freeze to the point deeming UE4 unusable 
P.S. ~30 min later still having freezes. After I closed Material Editor window freezes significantly subsided.
P.P.S. It feels like 4.13 constantly compiling shaders in the background. Btw, I not longer see a pop-up says and counting shaders when I change materials. It simply applies/saves and the, without any popup it goes into grind.