Is Python/Django performance significantly worse than Ruby/Rails? The situations you describe are things I do every day in Ruby. Getting 1000 rows from the DB and performing some operation only takes a couple of milliseconds in Ruby.
Ruby/Python are meant to be glue, and you can most certainly use them to glue together "interesting things", like image processing or audio processing in a web layer.
Memory caching rarely changed, often accessed, but ultimately persisted in a DB things like exchange rates in a global object is exactly what you do in Rails. There's a specific helper for doing it. http://api.rubyonrails.org/classes/ActiveSupport/Cache/Memor...
It's similar with Ruby/RoR - yeah, they can do async. But not on their own. With unicorn server, you still get no threading and just a bunch of processes. With puma you can do threading (async cooperative really) - as long as you keep the configuration/code within the limits of what's allowed.
And due to the extra care needed whenever you do caching/storage things, I expect unicorn is still the king in RoR deployments. (GH uses that for example)
What about memory usage? That's an un-appreciated axis, IMO: for example, all of crates.io takes ~30mb resident, which is roughly the overhead for MRI itself, let alone loading code.
Anyway, the Rust team loves helping production users succeed, so if there's anything we can do, please let us know!
If you want to do anything interesting, Python/Ruby are slow as hell, which is why you cannot do anything interesting in them.
For example, while in Go, you can load say 1000 rows from the db and perform some data manipulation on it in the code to get a desired result, you cannot do this in Python because it will very very slow.
So what you do is you write complicated sql queries and essentially offload all your work from the application server(s) on to the database server.
Now imagine that these rows on the database don't actually change very often. You could just load them once, keep them in memory (in a global object), and only update them once in a while (when needed). You can always do whatever search/manipulation operation directly on the data that is readily available and always respond very quickly.
This would be _unthinkable_ if you are using Ruby or Python, so instead you keep hammering your database with the same query, over and over and over again.