Consider the slinky again. If I dropped it with a parachute to slow it.... no, replace "parachute" with "my hand", but assume my hand follows the same trajectory the parachute would... the end of the slinky would not wait for my hand to approach it. The information about a change (the drop) would take the same amount of time to reach the end of the slinky. The information travels just as fast, even though the information is "we're falling slowly" instead of "we're falling".
Consider the slinky again. If I dropped it with a parachute to slow it.... no, replace "parachute" with "my hand", but assume my hand follows the same trajectory the parachute would... the end of the slinky would not wait for my hand to approach it. The information about a change (the drop) would take the same amount of time to reach the end of the slinky. The information travels just as fast, even though the information is "we're falling slowly" instead of "we're falling".