Overall performance might worsen
- Special-code mechanisms can speed up specific cases but slow down normal cases enough to cancel it out.
- Thunks are designed to have a low impact on unhandled cases.
- If ordinary execution would be fast, the function will not create a thunk, and the only overhead is a single size check.
- If a thunk is created but there's no special code, then the overhead is a fixed amount: 20-40ns. This is a bounded percentage of execution time.