Re: performance issues, offloading CPU-intensive operations to NIFs (or ports, if I/O bandwidth needs are low enough and you need to run something long-running)

Re: performance issues, offloading CPU-intensive operations to NIFs (or ports, if I/O bandwidth needs are low enough and you need to run something long-running) is a pretty common strategy for speeding up Erlang (and therefore Elixir) applications. It doesn't seem like the X-Plane folks have felt the need to do this, but it's definitely a possibility should they run into some computational bottleneck. Re: GC, the Erlang VM does it per-process ("process" in the EVM's sense, i.e. a preemptively-scheduled userspace/"green" thread rather than an OS process), so not only are GC operations fast, but they also only affect the process being GC'd. The immutability is also a factor here; since data is copied instead of modified in place, it's arguably a lot easier to know when to discard unused objects (namely: for an object to persist within a process, the recursive function(s) backing some process has to explicitly pass it along to the next invocation, so that's a natural place to discard everything else).