Does disabling cookies save battery?

Disabling them can waste time as you get to the portal and have to progress through pages to your landing page. Cookies are supposed to take you there by recalling where you left off. Misuse of cookies? yes, lots of thangs... https://www.google.com/search?q=Misuse+of+cookies&oq=Misuse+...

Not likely. More useful would be researching the advanced power management capabilities of your device (BIOS / Firmware settings, OS settings)

Blocking ads and other 3rd party content can reduce power consumption a little, as well as save bandwidth if you are on a metered data plan. Closing all apps not in use rather than letting them idle in the background can also reduce power consumption a little bit.

I'm using an extension with FF which claims to reduce the number of requests the browser makes for `extra' files and reduces your online tracking. Might be useful?

https://addons.mozilla.org/en-US/firefox/addon/decentraleyes...

If so, it would be such a minuscule amount that it simply doesn't matter.

Blocking ads and trackers certainly does, probably 2X time on a full charge