Perhaps not super-common, but at work we have to deal with XML files that are 4-500MB in size that don't contain newline characters. Every now and then we have edit them.

It's at least something I'd expect a premium text editor to handle without issues.

It's common when working with big API responses which are indented using plugins after loading. Most APIs do not serve whitespace in their responses, so it's crucial that the editor won't freeze up on initial load.

try turning off syntax highlighting, if you haven't. that speeds up ST dramatically on large files, in my experience.

or give UltraEdit a try. it opens huge files with ease.

If you are manipulating data, it could be. Logs can easily get big as well.

Yeah, plenty of people edit files like xml or json in text editors.

Sublime can do big files without any issue, the specific use case here is if it all sits on a single line. Most XML/Json files are not single line, but yes it happens.