[johannes1234321]

While that is true it can still be a good thing to use on a non-perofrmance critical path instead of adding a dependency on an external library.

Maybe it shouldn't be there and some better thing should be there, but given it exists ... as long as one is aware of alternatives using it is fine.

[ninepoints]

There's "not fast but usable enough" of course, but I would never ship std::regex code on any user facing software. Forget realtime, std::regex fails to be interactive in examples where other libraries resolve quickly.

[TylerGlaiel]

the last time I tried it (it was years ago) std::regex was taking a measurable number of milliseconds to evaluate which is kind of a very long time even outside of performance critical paths.