It's not like you can do arithmetic with references, so maybe the ergonomics of by-value vs. by-reference shouldn't really be that different. The cost of by-va

It's not like you can do arithmetic with references, so maybe the ergonomics of by-value vs. by-reference shouldn't really be that different. The cost of by-value lies in memory copies, while the cost of by-reference lies in dereferencing pointers where the values are needed, which might mean many more memory reads are needed than with by-value (depends on what you're doing). So it's just hard to tell which will do better in general -- there's no answer to that. For a library, maybe providing by-value and by-reference interfaces should be good (except that will bloat the library). For everything else just use by-value as it has the best ergonomics.