I just got a new PB (WR!) earlier today, so you can see the route I take. I do use the item blocks, like you suggested: Not sure if it's the fastest route, though.

Thanks! A possible route that might be faster is skipping the toad house in world 1 and getting the shell from the item box in 3-1. This saves 15-20s by not having to go into the toad house, but the downsides are that you swim slow for the first half of 3-1 and you don't have the shell in world 8. I'm not sure how much time shell in world 8 saves over fire (if it even is faster), but I'm more comfortable with the shell. I also messed around with doing 3-A instead of 3-1, but I don't think it's viable.

We decided to only take out loads for any% because it's by far the most competitive category. I won't be upset or anything if you beat my PB. If you think loads should be taken out then I could try doing that.