User option to ask cargo to leave out one core for other applications?

Hello, this is a small user experience feature request.

When developing at desktop, the compiler build will occupy all available cores, that will make the desktop system a little lagging. Wonder if we can provide a global option that alternate the default -j option value to leave one core out? Thanks!

I think you can set this in .cargo/config or via env var:

Ah, ok, i think this is what i want, thanks!