Ok, straight to the point: there is NO editor that can handle huge text file, size of giga bytes. I have this SQL file, 10+ GB, and no editor can handle it.
One commercial software I found is: http://www.textmaster.ca/
It claims it can handle 300GB file. It's nice, but I don't do this too often, so sorry, I don't want to purchase one. One easy way to go around the problem is, of course, splitting the file into multiple files and edit each, and later join the files together.
split -b 50m example.sql example_
cat example_[aa-bb] > example.sql
This will do.