I worked on a high performance Rails API serving dynamically generated map tiles and our response times were actually lower than that.
Sounds like an ideal case for fast response times honestly. I've seen rails endpoints like that aplenty. But there also exists a lot of stuff taking hundreds of ms on a cold cache, and it's the kind of thing where the same effort done in the same way using another language ecosystem would just be 10x as fast.
If you've never seen this, perhaps you've never worked with a large monolithic rails app with a few years of legacy code built up? Brand new API endpoints can be a lot faster of course.
10x faster in, say, Go? Are you sure? Have you benchmarked it? You might be surprised.
Lets pick a weakness of Ruby: tight loops and lots of math. Take 16,000 GPS points and calculate the geographical distance to another point.
On my machine it takes 12-14ms in Ruby and 4-6ms in Go. That's only a little bit more than twice as fast! Almost certainy not worth re-writing your entire app for.
I've worked with a bunch of large, legacy Rails apps. In between a couple of Rails jobs, I worked on a large .NET app, which didn't have much better performance. One service I helped migrate from Rails to Spring/Java for an enterprisey client actually got slower overall, despite moving to the JVM.
Sounds like an ideal case for fast response times honestly. I've seen rails endpoints like that aplenty. But there also exists a lot of stuff taking hundreds of ms on a cold cache, and it's the kind of thing where the same effort done in the same way using another language ecosystem would just be 10x as fast.
If you've never seen this, perhaps you've never worked with a large monolithic rails app with a few years of legacy code built up? Brand new API endpoints can be a lot faster of course.