tl;dr: I propose to rewrite, for example, swap_with_slice from this current version (source)

// Before (minimized)
pub const fn swap_with_slice(&mut self, other: &mut [T]) {
    unsafe {
        ptr::swap_nonoverlapping(self.as_mut_ptr(), other.as_mut_ptr(), self.len());
    }
}

to lift self.len() to the front as follows:

// After (minimized)
pub const fn…