Never fear, Emacs approach is pretty great. It uses a gap-buffer, which is conceptually an array with a space that moves around with the insertion point. It's pretty cool approach because, it's simple, there's very little bookkeeping overhead and moving around the gap is gonna generally be cheaper than shifting around the whole array and minimize complete re-allocations. In other words it's good for what we do the vast majority of the time with a text editor which is jump around reasonably size files making small edits.

One downside, relative to this conversation, is it doesn't make working with pathologically large files a lot better. Without further optimization a gap buffer could push your box into swap if you open a large enough file.