Well, the delegate-call aspect means that using your library is probably more expensive than using OpenZeppelin’s library.
And regardless of that, “memory push/pop” as a native part of the language is not necessarily going to be less expensive than either one of them (let alone both of them).
I’d assume that all of these factors have already been taken into consideration far back during the early days of Solidity, but let’s see what the Solc team members have to say about this…