informant に引っ張られた説

> possibly modelled after informant.
https://en.wiktionary.org/wiki/performant#Etymology

英語は古いフランス語の影響をモロに受けてるので、フランス語から借りてきた単語の変化もまたフランス語チックになりやすい、と

> Many words in -ant were not actually coined in English but rather borrowed directly from Old French, Middle French or Modern French.
https://en.wiktionary.org/wiki/-ant#Usage_notes
QT: https://misskey.caligula-sea.net/notes/9pp62n0s5p [参照]