Electron 1.6.2 is currently using Node v7.4 - according to their website.

Here's the v7 release notes, but here's some highlights that are relevant to our interests:

• Promises: Unhandled Promise rejections have been deprecated and will emit a process warning promise: warning on unhandled rejection nodejs/node#8217
• V8: Fixed a significant instanceof performance regression deps: cherry-pick 08377af from v8 upstream nodejs/node#9730
• Buffer: Improve performance of Buffer.from() by ~50%. buffer: improve allocation and from(arrayLike) performance nodejs/node#10443

I've had v7 running on my Windows VM for a few weeks, but haven't noticed anything unexpected.

We've already been using NPM v4 on Appveyor and Travis (coming soon #1084), but here's all the v4 release notes (and subsequent updates) for you to soak up https://github.com/nodejs/node/blob/master/deps/npm/CHANGELOG.md#v400-2016-10-20