Why is it unfortunate? The English language is built on an endless supply these mutations.

Just taste really, it sounds wrong to me.

On the scale of new words I dislike, it's nothing compared to how football pundits describe players as 'unplayable' when they're on form.

On a scale of new words I dislike, it's actually more annoying to me than "revert back" meaning "get back to you on that", which has a wry charm.

Mind you, I am still annoyed by people saying "addicting" when they actually mean "addictive", or "concerning" when they mean "a cause for concern".

So I'm really not a good judge. But it still has to go in the circular filing cabinet.

If we were better at keeping -ive suffixed words, we could have had concernive instead to shorten that phrase without misusing -ing. :)

Now you're just trying to upset me. ;-)

Greetings, fellow curmudgeons!

Surely the worst word to come out of sports pundits is "winningest"

Words are only ever added to the OED after a period of use.

Before performant made it into the OED as an adjective, the nominal form was listed as a "nonce-word" only and didn't merit its own entry; it was kept under performance. It was never widespread in any dialect, unlike modern performant.

-Ant/-ent is not reserved for nouns anyway. There are informants, inhabitants, defendants, and many others, of course, but they can be ignorant, hesitant, pleasant, constant, tolerant, conversant, triumphant, significant, vigilant, dominant, compliant, adamant, reluctant, elegant...

Some of the second group fall into both categories, adjective and noun. Frequently the one form came later than the other. Add performant to that long list.