Late Stage Capitalism

old webpages (like from the 2000s) are fast and snappy. new webpages take much longer to load.

This part is true, especially on phones, but those old webpages were not fast at all when they were first published.

I remember trying to watch videos on dialup Internet. I'd make it start buffering and then go do something else for half an hour before coming back to watch the video. I also remember avoiding certain websites even on DSL because they had 1 or 2 whole megabytes of JavaScript and it took forever to load.

Increases in bandwidth and processing power has made those old websites seem a lot more performant than they were at the time.

Today we can put a lot more stuff on our websites than we used to, which makes things slower, but we're also much more aware of major performance issues. Google uses it as a factor in their ranking algorithm, and offers a pretty intelligent tool to help developers figure out where to optimize their websites, so it's essential for most companies to optimize for that. Giant companies like Amazon and Facebook can ignore it because they'll always be on top, but the rest of us are getting really excited about new frameworks like solid and qwik that will make it a lot easier to optimize our sites.