Well just the fact that a structure can fit in one cache line vs ten is a start. A lot of the systems I deal with aren’t “ephemeral” meaning the data gets copie

Well just the fact that a structure can fit in one cache line vs ten is a start. A lot of the systems I deal with aren’t “ephemeral” meaning the data gets copied out of Eden into survivor and then tenured just in time to die. What else. Interfaces uses that don’t always point to a single type so they don’t get hard coded. Interfaces are quite a bit worse than even abstract base classes in Java if they actually have to be decided upon. Most of the time you’ll be doing that same behavior in Rust using enums rather than dyn. Lets see. “Clever bit tricks”. So like fitting a Set implementation into a cache line if it only has 8 element and using a regular hash set if it’s bigger. So much opportunity.