I find this to be a very amusing critique. In my experience, Notion (when I stopped using it 3 years ago) was slow as molasses. Slow to load, slow to update. In comparison, at work, I almost exclusively favor Confluence Cloud. It's very responsive for me.

We have tons of Confluence wikis, updated frequently.

I think it might be the same issue as with WordPress and Jira - terrible plugins. Each company uses own special mix, and encounters issues often occurring in that one specific configuration. And it is the base platform that takes the blame.