The linter was the issue.

I actually have better performance with Sublime Text and JavaScript than I do with vim and JavaScript. I wish that weren’t the case.

If you know if any better ways to get vim working with Syntastic for linting (eslint), I would love to know.

Agreed, if anything will slog a text editor it is usually the linter

Also, you can choke vim with large (>5gb) test files. Or is that fixed now?

The irony is that sublime text doesn’t slog down

Sublime Text and TextMate will both choke big time if you feed them a large enough file without any line breaks. I have some largish machine-generated (5-10 MB) JavaScript data files that will reliably bring either editor to its knees if I accidentally click on one of them. The XCode editor also chokes.

I seem to recall (though haven't tried it for a while) that the Visual Studio Code editor handles them okay.

It's not a big issue -- since these are machine-generated, it's not normally necessary to edit them by hand. Every once in a while, though, I'll accidentally click on one of them in the file tree. Then I'll curse and kill the editor process.

Switch syntastic for ale: https://github.com/w0rp/ale It's asynchronous if you're running vim8+

Awesome, thanks for this!