In reply to Summer.

Awesome to hear Summer!! So glad you're enjoying it. You can definitely enable shortcodes in widgets with a simple filter, but sometimes themes will enable this, so we leave that to them.

It should work super fast with lots of posts! It will return the results as fast as the REST API on your site can return them. The API just does a normal search query behind the scenes, so "theoretically" it should be as fast (it not faster) than searching for a normal post.