Ruby isn't standing still in terms of performance either. YJIT is getting better all the time and ZJIT is on the horizon too.
For concurrency, async fibres are brilliant but not the only game in town.
Using good old processes works really well in Pitchfork or alternatively JRuby and TruffleRuby both have true non-blocking parallelism right now using Threads.
If anything TruffleRuby shows that there is nothing inherient in the Ruby language that means it cannot catch up in performance terms.
For concurrency, async fibres are brilliant but not the only game in town.
Using good old processes works really well in Pitchfork or alternatively JRuby and TruffleRuby both have true non-blocking parallelism right now using Threads.
If anything TruffleRuby shows that there is nothing inherient in the Ruby language that means it cannot catch up in performance terms.