Loco? https://loco.rs/

Elixir + Phoenix?

Indeed. Runtime is typically a lot faster than Rails. Response times in dev mode are <1ms which is fun to see coming from Rails :)

My personal dev speed however is a little slower in Phoenix than Rails. And I've been using Rails for almost 20 years and Elixir for 10.

There are categories of problems that are much easier in Elixir (High concurrency, low latency, etc) and for those I would always pick Elixir. If you're planning "just" a crud like web application, Ruby will probably get you to product-market-fit faster. There are (well maintained) gems for almost everything.

Laravel or Symfony using PHP

Ruby is plenty fast these days (people usually think Ruby didn't get faster but it did). And if we figure out how to switch to async/fibers with let's say Falcon, we are in a good place :)

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.

Speed of the language is not a problem for 99% of projects