Chrome recently introduced some changes to background tabs (to a bit of grumbling from sites that wanted to use background resources/service workers):

https://developers.google.com/web/updates/2017/03/background...

And also - they're aggressively throttling background tabs:

http://blog.strml.net/2017/01/chrome-56-now-aggressively-thr... https://news.ycombinator.com/item?id=13471543

I'm on Chrome Canary - and there's been noticeable improvements in memory/responsive wise for a few months now.

I have around 320+ tabs open, spread over 2 Chrome profiles (around 160 per profile).