Check your system performance, clean processes, who are using ram.
My firefox takes sometimes up to a gig with all those tabs and even skype raises from 30-600mb.
I have Ramrush(Freeware) running, but i do not use the autotweak option, but it shows me exactly, when i have to restart launcher and editor, before mess starts.
Important part is, that you have your cache on ssd, ue4 would be great there yes, but it is using so much space.