Through inlining. If you have something like a `while` loop and that while loop's instructions fit neatly on the cache line, then executing that loop can be qu

Through inlining. If you have something like a `while` loop and that while loop's instructions fit neatly on the cache line, then executing that loop can be quiet fast even if you have to jump to different code locations to do the internals. However, if you pump in more instructions in that loop you can exceed the length of the cache line which causes you to need more memory loads to do the same work. It can also create more code. A method that took a `foo(NotFinal& bar)` could be duplicated by the compiler for the specialized cases which would be bad if there's a lot of implementations of `NotFinal` that end up being marshalled into foo. You could end up loading multiple implementations of the same function which may be slower than just keeping the virtual dispatch tables warm.