I'm new to this place and Sonic in general, so I'm not exactly sure if this is new, if it saves time, or if it's even in the speed run route.
Well anyways, I know about the really high bounce trick against the wall in SA2B. I'm not sure if it's just me, but you have to be at a somewhat far distance to use it, then spend a few frames jumping and bouncing. But in Metal harbor, you can get a similar result by standing on the square platforms attatched to the red crates and spindashing while pushing the control stick against the crate. The only place this can probably be of use is at the first pulley in Metal Harbor. Once you skip the weird half loop thing and jump over the ramp at the end of it, immediately jump to the right and land behind the red crate, and without wasting time, spindash while holding down on the control stick. There's nowhere near the 2nd pulley where this would work. Unless a fully-charged spin could potentially skip both pulleys (I haven't tested this trick much).
For all I know, the normal superbounce or even just taking the pulley is faster, I'm not sure.
At least this could be used in a hero-side story speedrun because you wouldn't have the bounce ball by Metal Harbor.