> Nah, it's a pretty known fact. This is a case that Spiderman's uncle talked about: "With great power comes great responsibility".
With the possibility to tweak Emacs anyhow one likes, that also increases the chances of one badly tweaking Emacs. One should not blindly paste configs from other users; one should know exactly what their config is loading. Most of those search results will talk about using `M-x profiler-start` which allows a user to understand what in their Emacs config is causing it to slow down (this exercise, which many people do not do, and just complain about it being slow). If people find their Emacs slow, they should compare with how fast the `emacs -Q` (stock emacs with zero user config, but still fully functional) sessions are. Emacs allows users to customize every aspect of their editor experience and that can be too easy to shoot in one's foot too.
