Automatic tagging of cards is an interesting idea, we could add a after-rating hook so it's easy to add custom logic like this.

I think we should figure out a way to support different spacing algorithms first, then see where this can fit in (e.g. how should it work for algorithms that don't have a concept of ease?).

-- l3kn

Issue is on hold until multiple spaced algorithms are supported, and the definition of "low performance" is abstracted out so it can be used with multiple spaced repetition algorithms.