Wow! The new version of V8 "…reduces peak memory consumption of on-heap memory up to 40%." and reduces "…off-heap peak memory usage by up to 20%". As the author of a large Electron app that has huge implications downstream for our users. Great job!
It looks like this optimization is for low-memory devices which probably doesn't apply to what you are targeting with your Electron app.
Keep in mind that this blog post is talking about V8 memory and not Chrome memory. The percentage for Chrome is obviously lower.
I tried to tracking down what progress between versions looks like, but couldn't find anything solid in my few minutes of googling.
https://github.com/electron/electron/tree/master/vendor -> node