Is it better for performance to disable unused default core views?
I am not using any of them. Is core expecting these to be enabled?


They are just examples and can be disabled if you don't need them.

The taxonomy term view is a bit different because that is the one that provides list of content when clicking on a term, if you disable that then those pages become practically meaningless as all they do is show the term with its fields.


  Does disabling these actually improve performance in any way?


Most likely not a in a measurable way. There are a handful of routes less due to that that don't need to be regenerated on a cache clear but that's a tiny amount of the total routes and it should have no impact on runtime performance.