Chrome M87 comes with Tab throttling and other performance improvements. The internal tests done by the Chromium team have displayed a reduced CPU usage by up to 5x and an extension to the battery life up to 1.25 hours.
M87 also brings Occlusion Tracking (that allows Chrome to identify visible windows and tabs) for Windows users, a feature already available for Chrome OS and Mac. This feature is also a resource-usage optimization one.
Last but not least back/forward cache is a browser optimization for faster back and forward navigation.
Read more about it here:
Tab throttling and more performance improvements in Chrome M87