How to match 2 huge size list #2

Question

I got a precious answer from Vishal Balaji who suggested me on to use of set() for improve speed in list intersection. For whom can't understand what does mean intersection , here is the link ;-).

delta = list(set(tit_comp)-set(out))

this helped me a lot, but now I need a further step up in velocity, because the lists to manage are in order of over 10^6 items(strings of max #10 char) each and the computing time is becoming incommensurabile (always for whom don't know it: means to much time to be count that imply the above intersection take too to long time to wait it finish for a reasonable time).. Even splitting the list in chunk the computing time is huge. I also facing with a mem overflow crash
any suggestion on how to solve the enpass ?

I'm finally asking if anyone knows a different way to treat the huge lists..

thanks