sized free is good for safety if your malloc cross-checks the size argument with its metadata, and for performance if your malloc assumes the size argument is c

sized free is good for safety if your malloc cross-checks the size argument with its metadata, and for performance if your malloc assumes the size argument is correct without having to hit malloc's internal metadata. There's also a middle ground where you get more ILP by assuming the size argument is correct (for performance), and overlap the work of `free`ing memory with a confirmation that the size argument matches malloc's internal metadata.