Kakoune has been my main editor for the past year (give or take) and uses an array of lines [0]. Ironically, multi-cursor and regex are some of the main features that made it attractive to me.

I just tested it out on the 100MB enwik8 file I have laying around and it does slow down significantly (took 4-5 seconds to load in the file and has a 1 second delay on changing a line). But that is not really the type of file you would be opening with your main editor.

[0]: https://github.com/mawww/kakoune/blob/2d8c0b8bf0d7d18218d4c9...