Spent an afternoon to save 5 kB in a JS script in one of my WordPress plugins that is installed on close to 2 million websites.
That's 5 kB * 2M = 10 GB.
Assuming an average of 10K of monthly visitors per site, that is 10 GB * 10.000 = 100 TB saved per month.
At 5 kWh per GB of transferred data, that is 500.000 kWh or ~400.000 kg CO2.
TLDR: That 5 kB saves approx. 400.000 kg of CO2 emissions per month.
I'm going to hunt for more kB's over the next few days, as it's clearly the most effective use of my time by a long shot.
Personal Mastodon instance of @danny.