Yeah, the bloatloads of javascript are probably the worst offenders of ignoring performance of software other people have to run, sometimes even reimplementing features the browser already has, just slower and worse (Listen Zendesk, my browser has been doing tabs just fine for a decade, implementing them in javascript and entirely hijacking normal browser navigation behavior doesn't make anything better for anyone).

Thinking over it some more, browsers themselves were probably not a good piece of software to call out on performance considering how much optimization is actually done to increase their performance. The horrid things people do on top of them deserve all the blame they get though, and then some.