It was deliberate. Performant is the adjective of performance, so describes the APIs as having high performance

I'm not the only one who was surprised by this. It was a usage I, as a native speaker, had never heard before. But I'm not a prescriptivist. As long as it's intentional, who am I to say it's wrong?

Both OED and Cambridge now consider it a word, particularly in a technology-related context. Out of interest though, it's first known usage isn't tech-related at all - Samuel Coleridge used it in the 19th century

Both OED and Cambridge now consider it a word, particularly in a technology-related context. Out of interest though, it's first known usage isn't tech-related at all - Samuel Coleridge used it in the 19th century

It looks like that first usage is an obsolete definition meaning "the person who performs something," similar to "referent" or "defendant".

Not to get into a linguistic squabble but... the verb+ant form of many roots can be used as both noun and adjective.

Note that this isn't the case for referent as it is direct from the Latin referent however for defendant both usages are valid.

See https://www.merriam-webster.com/dictionary/defendant

I would post OED's corroboration but it's paywalled unfortunately.

Though really we're not comparing apples anyway. A change from high-performant to either performant or high-performance is probably valid.

Specialisation of an adjectival form via hyphenation is either obsolete when the adjectival form (performant) already supplies an affirmation or misleading if it attempts to further qualify it (e.g. low-performant does not make sense)

FWIW, I think this is a valid change - "performant" is a valid adjectival form, but in this context "performance" is more grammatically idiomatic. (Try saying that five times fast...)

Yaaay the language nerds have come out to play! I think Gwynne's point about it being idiomatic is the best summary of what I was going for. "High-performant" just isn't a common wording, whereas "high-performance" is. (It's also a lot of syllables to say "fast," but I guess it's idiomatic for computer stuff?)