Since when did we start using file size as a measure of efficiency or optimization?

Off the top of my head: $() CSS parsing and DOM traversal was way slower than querySelector or getElementById, both of which predate jquery by years. Every $('.my-class') created wrapped objects with overhead. Something like $('#myButton').click(fn) involved creating an intermediate object just to attach an event listener you could’ve done natively. The deeper the method chaining got the worse the performance penalty, and devs rarely cached the selectors even in tight loops. It was the PHP of Javascript, which is really saying something.

By the early-2010s most of the library was dead weight since everyone started shipping polyfills but people kept plopping down jquery-calendar like it was 2006.

(I say this as someone who has fond memories of using Jquery in 2007 to win a national competition in high school, after which I became a regular contributor for years)