The only thing that is passed "efficiently" between processes are large binary blobs. Everything[0] else is copied. Up to a point, this is efficient, as a copy

The only thing that is passed "efficiently" between processes are large binary blobs. Everything[0] else is copied. Up to a point, this is efficient, as a copy decouples sharing and this is really good for modern caches, and it is good for the garbage collection. However, when the data becomes too large, Erlang programmers often choose to bring the computation to the data rather than the other way around. Passing a function is efficient. Keeping data cache-local in a process is efficient. [0] Except literal data.