Maybe a bit late on the battlefield reply, but i had the same problem.
I just found the most recent official ZTE stock rom (and kernel, thats the thing thats bugging and sometimes force closes apps)
Rooted it, installed that crappy app called Clean Master, use it to delete the bloatware (like Gmail, Hangouts, Share, TouchPal and all the other sh*t that eats ram and does nothing) you should also delete the rest of bware manually IF you know what you are doing. Put that '1 touch boost' widget on your screen and use it whenever you wanna do something on your phone.
should have like 120-190 free RAM if its successfully boosting.
P.S. I'd put links for stock but it leads to another forum about android development, i think thats forbidden here so just PM me if you need it