They noted that wake-ups in background pages are currently limited to one wake-up per second and about 1% of CPU use. Google's experiments test limiting these wake-ups to one per minute.
The Chromium team ran one experiment on Chrome with 36 background tabs and the about:blank tab in the foreground, and a second experiment with 36 background tabs and YouTube in the foreground playing a video in fullscreen. The background tabs included popular sites like Twitter, logged in Gmail, Amazon, and Best Buy.
Using a highly-specced MacBook Pro 15-Inch 2018, the group then tested how long it took to drain its battery on Chrome with no throttling, Chrome with throttling, and Safari 13.1.
Even with throttling turned on in Chrome, the MacBook battery was drained faster than Safari in that configuration. However, the throttling puts Chrome much closer to Safari's impact on battery life than previously.