fix(startup): save startup time, thanks @rem, closes #40

[janl]

Thanks @remy!

[boennemann]

Whenever you initiate the update notifier and it's not within the interval threshold, it will asynchronously check with npm in the background for available updates, then persist the result. The next time the notifier is initiated the result will be loaded into the .update property. This prevents any impact on your package startup performance. The check process is done in a unref'ed child process. This means that if you call process.exit, the check will still be performed in its own process.

I think this is already taken care of/this change doesn't make any difference.

[janl]

I could measure ~70ms time improvement consistently on my MBP

[boennemann]

I just wanted to add, except for the time it takes to load the library itself into memory. But this also means the notifier is only ever called when the command doesn't fail, which isn't that cool, given that a lot of fails could result from the CLI being outdated.

[janl]

good point, ignore.

[boennemann]

Addendum II: The defaults operation could be quite expensive. We could probably speed this up by just picking name and version first, and then applying the defaults.