This can be seen in the assembly generated by the `get_unchecked` function. Although there is no bounds checking on the array, it still checks whether the entry is occupied and so there is a branch and panic handling code due to the use of `unreachable!()`. I think that logically, both kinds of checking are the same type of error (you accessed an invalid index), so it makes sense for `get_unchecked` to do no branches at all, only address arithmetic.

The only open question is whether the documentation should be adjusted to use a term other than "bounds checking" here since the set of valid slab indices is not an interval.