For some reason I detest the word performant ..it has become a real word but is basically techie jargon..it’s irrational but it really gets on my tits!

For me it depends.

If I see a dev framework pitch written for devs described as ”A performant alternative to React Router” I take it seriously.

But if I see a powerpoint from a business person saying ”the new login page will be performant and …” I kinda assume they just threw that word in there and they might be less serious about making compromises to increase performance than if they wrote something like ”performance optimization”

Another example why English sucks

As usual, "performant" has different meanings depending on the area of expertise. A performing authentication system is fast, a performing login page offers a streamlined user experience, a performing ad banner campaign generates loads of clicks, a performing stock has gone up faster than expected...

Jargon is industry-specific. Always has been. In a lot of languages - not just English.