[gfody]

there's a great but not well known editor for windows called EmEditor that has a strong emphasis on performance and large file support. afaik the author has a background in low level performance optimization from Intel. if you work with large csv and/or json files you want this editor - it's amazing!

[fomine3]

Suzukawa Editor (Japanese shareware) is interesting project. It claims it's the best editor for huge gigantic file. It compares with EmEditor in official page and it performs unmatched performance.

I haven't used this because I have no chance to edit such gigantic files.

https://szkwjp.sakura.ne.jp/

This is a world ranking with other editors by the author, maybe others are suitable for non Japanese users.

https://szkwjp.sakura.ne.jp/bigtexteditors.html