I don't know if this is known or not because in the Any% guide it's says nothing about any difference in the tap delay assist except that hold is faster but I've tested it on the saloon fight and using 4x instead is noticeably faster getting out of Tommy's scripted grapples, Instead of taking five elbows for the first grapple it's only two with the 4x assist. first scripted grapple is at 46 seconds in the video and the second one is at 1 minute 13 seconds:

I don't know if it's already been found but diving can skip Arthur's Dialogue it's about at 50 seconds