Each module, and every function in every module is an atom. If you are loading a few libraries hitting 22K isn’t too hard. I’m not sure what to think of the memory. Its not so bad compared to other high-level language VMs though is it? I’m sure Go or Rust would be a lot smaller but a better comparison is Ruby, Python or Java.

70 MBs seems a bit high for a small app. What all libs are you loading?

The image below shows a basic Phoenix app.

image478×254 8.74 KB

If you do try building a release, I’m curious to see what the memory usage turns out to be. I made a quick comparison in a project of my own and also just a plain new phoenix project, in both cases memory use was much higher in the release. Why do releases use so much more memory than `mix run`? - #2 by michalmuskala

As I point out though, my comparison may be unfair, as not all code is necessarily loaded in the mix version when I checked memory use, while releases preload all modules. But you should be able to get an accurate comparison.