Problem is so many websites are slow for no good reason.

Bad coding is a part of it. “It works on my system, where the server is local and I’m opening the page on my overclocked gamer system”. Bad framework is also a part of it. React, for example, decided that running code is free, and bloated their otherwise very nice system to hell. It’s mildly infuriating moving from a fast, working solution to something that decided to implements basic language features as a subset of the language itself.

Trackers, ads, dozen (if not hundreds) of external resources, are also a big part of it. Running decent request blocking extensions (stuff like ublock origin) adds a lot of work to loading a page, and still makes them seems more reactive because of the sheer amount of blocked resources. It’s night and day.