[nthj]

They talk about reducing memory allocations. My guess is the rest of the app is very large and they’re benefiting from not sharing memory and GC with that.

Of course, everything you said is true for a small-to-medium sized Rails application.

They likely could have explored a separate Rails app to meet this goal, but then they have to maintain the dependency tree and security risks twice. And if the Rails core refactors away any optimizations they make, they have to maintain and integrate with those.

There’s definitely some wiggle room and a judgement call here but their custom implementation has merit.