“improves battery life by up to 0.5%”
To me this line is quite ridiculous.
We all know that Chrome is now the main responsible for battery consumption on any laptop and could be optimized much more.
But it's still tiny in a relative sense.
Edit: Had a go at putting some numbers on that for fun, and will partially retract my comment (no I don't, see below).
If it takes [1] around 0.01kWh to charge a smartphone, there are [2] around 6 billion smartphones, each is charged once a day and this saves 0.05 (wrong,see below) of that usage, the saving is on the order of 3GWh/day, i.e. around 125MW.
Total global energy consumption is [3] around 20 TW, so the saving is around 0.0006% of it, and this is a very generous estimate (chrome isn't all the consumption of a smartphone, not all phones are in active use and charging once a day, etc).
That said, in absolute terms it's more than I would have guessed - comparable to the electricity consumption of a small town (no, much less, probably less than the output of a single wind turbine - see below).
[1] https://www.quora.com/How-much-in-kwh-does-it-take-to-charge...
[2] https://www.statista.com/statistics/330695/number-of-smartph...
[3] https://www.theworldcounts.com/stories/current_world_energy_...
Edit 2: On reflection, I think this is an big overestimate. I suspect the real saving is on the order of a few MW.
Edit 3: As the reply says, I missed a zero, which brings it down to probably on the order of a MW.
If everyone who is in a position to reduce the energy consumption of their small part significantly does their part then it will add up to a significant effort.