If you just want to view
large files, try the marvelously named Large Text File Viewer
. (Just like Space Shuttle - it's called what it does. Gotta love that!) It's small, free, and doesn't require installation. Unpack it in a folder and you're set to run.
Download link at: http://www.swiftgear.com/
I used LTFV on a project where one huge file was crippling just about everything I tried to load it on. LTFV worked like a charm. One download site had a reviewer that claimed it opened a 40Gb file without a hiccup. Not sure if I believe that one (mainly because I can't imagine what a text file that big could possibly be used for) but it took my 2.26 Gb text database - complete with a seriously pooched file header - without blinking twice.
Note: the search feature can sometimes be a little slow if that is important to you.
I'm pretty sure my current fav text editor (Notepad++) could handle a file that big, but I can't say for sure since I don't have currently have any text files that size to test it with.