I've been working in the web performance monitoring space (https://speedcurve.com/) for 3 years now, and the 3 years prior to that I was doing a lot of performance work at the BBC. I can't share the data for obvious reasons but I can confidently say that the web is getting measurably slower every year, despite connection speeds increasing drastically over the last few years.
We like to over-simplify and try to attribute it to things like JS frameworks, advertising, media-heavy pages, etc. The truth is that it is all of these things, and so much more. Yes, devices are more powerful, but we are also asking our devices to do more. Yes, connections are faster, but bandwidth doesn't help with things like TCP slow start or browser concurrency limits. On top of all of this, our perception of speed is changing, so things can _feel_ slower than they really are.
We like to over-simplify and try to attribute it to things like JS frameworks, advertising, media-heavy pages, etc. The truth is that it is all of these things, and so much more. Yes, devices are more powerful, but we are also asking our devices to do more. Yes, connections are faster, but bandwidth doesn't help with things like TCP slow start or browser concurrency limits. On top of all of this, our perception of speed is changing, so things can _feel_ slower than they really are.