First I am a hobbiest. I dont have cutting edge systems. I own a desktop with 8GB Ram, 2GB GeForce GT 640 & Windows 8.1. My laptop is a newish Inspiron 7 7000 with 6GB Ram & dual Intel / Nvidia card ( 2GB ).
On Both systems UE is getting to be painfully slow and unusable - taking ages to load projects from market etc. When loaded some are slow also.
It seems - unless you have a serious system with loads of resources - you are wasting your time with UE as a hobbiest.
I am going to drop my sub this month - might check back in in a few months see if things have improved.