I used to use Borland's Brief to edit large files. But it is commercial. There is a free version in beta here https://sourceforge.net/projects/grief/ https://so

I used to use Borland's Brief to edit large files. But it is commercial. There is a free version in beta here https://sourceforge.net/projects/grief/ https://sourceforge.net/projects/grief/ Grief. It pages the file in and out of memory to save space.