I hope this one is obvious, but since it is a current limitation in CE, I wanted to post it here to be a "feature" of EE. (CE may have a limit of "words" instead of characters, but anyway...)
From time to time I have to manipulate large matrices of data in text format. Unfortunately, CE has the above mentioned limitation, which causes extremely wide lines to be completely uneditable or even viewable (sometimes it will even crash). This is actually one of the only reasons I keep TextPad around (which handles the huge text files flawlessly), the other being for simple file comparisons, which I hope to see in a plugin, if not in the core codebase. I've started moving my coworkers from TextPad to CE coworker by coworker, as CE's block edit or columnar mode is vastly superior to TextPad, IMHO, which is very handy for languages like VHDL, but really wide text files need to be processed by use from time to time, so TextPad will be sticking around for a while. On the other hand, CE does a fine job with files with many, many lines, though I'll sometimes run out of digits in the line numbers.