I think Luminus still uses Immutant by default

And I believe Luminus is still very popular with new projects. Of course, it's easy to use an alternate server

Immutant and Aleph are both good web servers. I have a perf-fork of Immutant, but sadly don’t have time to finalize & do a PR from it. Would have: real zero-copy requests, better NIO and async support and more perf options to tune with. There is big potential, just no time (and I’m not involved with Immutant / Red Hat, just using it (and Aleph too))

that “immutant” is the perf-fork.