So van Kooten decided to slim things down. He “refactored” his plug-in, making it more efficient, so now it sends 20 KB less data. Overall, the site would use a little less energy every day.Of course, 20 KB is a teensy reduction. But since 2 million websites use his plug-in, it adds up. By his crude estimate, trimming the code reduced the world’s monthly CO2 output by 59,000 kilograms, roughly the equivalent to flying from New York to Amsterdam and back 85 times.