vDSO getrandom has been in the kernel for what, two weeks? And it is only "super fast" compared to the unbelievably slow full syscall. Compared to PCG it is like watching rocks grow.
Linus merged it on July 24, 2024, so about a year I guess. Kernel is released ~8 weeks after the merge window, so I suppose September or so.
I think neither are unbelievably slow. I dunno, take some measurements and see, maybe it suits you.