Copying data is usually necessary in OTP 20 as well I'm afraid. That new optimization doesn't trigger for most of this. But binary data is not copied and hasn't been since at least OTP11 :)
The release says "Erlang literals". Wouldn't that be things like atoms, integers, booleans, tuples, and the like? That plus binary data should cover a good deal, unless I'm reading too much into the blurb on the release notes.
Under what circumstances does it get triggered (since you seem to be more knowledgable about this than I am!)? I expect records would not fall under this.
A "literal" in this case is a constant value defined in a module. Those live in a separate space in the VM and are referenced directly because they are immutable and can be shared. If you sent such a literal before OTP20, it would be copied into the heap of the target process. Not anymore.
