When star unpacking positions into a function we can avoid a copy iff there are no extra arguments coming from the stack. Syntactically this looks like: `f(*args)` This reduces the overhead of the call by about 25% (~30ns on my machine) based on some light profiling of just * unpacking. I can imagine this having a slight impact on code that uses this feature in a loop. The cost is minimal when we need to make the copy because the int != 0 check is dwarfed by the allocation. I did not notice a significant change between the slow path and the original code. The macro benchmark suite did not show a difference on my machine but this is not much more complex code.