[KerrAvon]

BBEdit can (and always could) read text files significantly larger than RAM without thrashing VM. This has always required a custom text engine, first because it was the only way to do that, and more recently I assume it still provides highest performance.

[rvense]

When it started, the native text editing on the Mac was limited to 32K chunks! Need anything more, you could start with the raw APIs that lay out a single line of text and do it by hand.