I learned that not all text editors go to the effort of loading the file data very carefully with careful underlying data structures when I tried to open a 67K LOC COBOL file on a 32bit system, a while back. (Sidenote: COBOL has a 999,999 LOC hard limit in the compiler spec.)
So very many editors just couldn't open it.
Some would use so much memory that the system would either freeze, or the OS would kill them.
Some would silently truncate at 65,535 lines.
Some would produce a load error.
Some would pop up with an error indicating the developer thought it was an unreachable state. e.g. "If you're seeing this error... Call me. And tell me how the fuck you broke it."
Others would manage to open it, but were completely unuseable. Where moving the cursor would take literal minutes.
There were exactly three editors I found at the time that worked (none of which were graphical editors). And they worked without any increased latency, letting you know that the developers just thought through what they were doing: vim, emacs, nano.
(A few details because people are probably curious - the vast majority of that single file project was taxation formulae. It was National Mutual's repository of all tax calculations for every jurisdiction that they worked in, internationally, for the entire several hundred years of the company. They just transcribed all their tax calculation records into COBOL.)