Wordpress - Do multiple revisions really slow down WordPress?

Having 2 revisions or 100,000 will not change front end performance in a default plugin-less WordPress setup

However plugin and theme authors who do not query the database correctly, could end up accidentally searching/querying revisions, which could have some performance issues

Here’s a snippet on it

revisions take up space in your WordPress database. Some users believe that revisions can also affect some database queries run by plugins. If the plugin doesn’t specifically exclude post revisions, it might slow down your site by searching through them unnecessarily