When data mining comes up a fast visual inspection of the file is often imperative. If this file is very large (> 2 gig) chances are Your ordinary wordprocesser and PC will freeze. A bad start that is also bad for Your health and stress levels.
What You need is Jalatext and 30 $
Written in Java, Jalatext is capable of opening very large (1 gig+) files almost instantly. Rather than churn madly trying to fit as much of the file as possible into RAM, it loads a small portion at a time, keeping performance swift. The user can adjust the size of the loaded segments, in accordance with their available RAM.