https://twitter.com/Really_Tall/status/728640763660226560
Confirmed this saves time in Any% as you also skip the text for getting 3 stars! Somewhere from 1-5 seconds depending on how fast it can be done: ideally the star would be spat out right after you land from the twirl, and then you'd go straight to the loading zone, but that may not be possible in practice.
The mechanics of spitting out a star are very strange: sometimes the star will keep going forwards and upwards and be unobtainable, and sometimes it will just go forwards, and be collectable. The speed it travels at can also vary wildly. From what I can tell, spitting it out just before/after you land is the best way to make it tangible, but if you're not moving backwards then you will collect it almost instantly. Being damaged by an enemy will also make you release the star and it will travel at around double the usual speed.
I'm not sure if this glitch could save time in other courses, in the 150 Star TAS. The glitch requires an owl, shell, spindrift or fly guy to work, which means it is possible in most courses, but for it to be useful the course has to have a loading zone in it. This means that CCM, JRB, LLL, SSL, SL, TTM and THI are the candidates.
In CCM the loading zone is very far away from the stars, so it is unlikely to save time.
IN JRB, the only loading zone is underwater, so there isn't really any hope.
In LLL it will likely save time, but only if it's possible to start riding a shell that you have spat out anywhere. I know this is possible if you spit the shell out while on a steep slope, but I don't know if it's possible anywhere: trying to jump on the shell will usually damage you.
In SSL this will save time, but the route may need changed. You could in theory do this glitch with any of the stars outside the pyramid, and then either exit course or get a star inside the pyramid after... there are quite a few options to test.
In Snowman's Land, for some reason, this glitch actually doesn't work on the igloo. The star will just bring you out of the course like usual. The loading zone is actually delayed: if you do this with the 100 coin star then the loading zone will continue talking you afterwards. This is unfortunate as it could have saved a decent amount of time :/
I haven't tested in TTM yet, but there is a good chance that the loading zone will work the same as the igloo, as it does the same zoom effect. Otherwise it could be useful, but it's unlikely.
In THI there are a lot of loading zones to work with, but luring a fly guy somewhere is ridiculously slow (
https://twitter.com/Really_Tall/status/728665830259593216). If it's possible to take a Koopa in your mouth to the top of the course quickly then it could save time, and more testing needs done.
In addition to all this, doing this glitch with one of the stars that appears for a limited time when you hit a switch has some pretty crazy effects. When the timer runs out most objects, such as enemies, penguins, blocks, etc., will freeze and you can pass through them freely: the effects are similar to timestop in the original SM64. I will make a video of this in full soon: but for now:
https://twitter.com/Really_Tall/status/728560745781334016
This actually works as an alternate method for doing Slip Slidin' Away and Big Penguin Race BCCless since you can pass through the coins blocking the chimney, and it's probably faster. Loading zones are actually disabled while timestop is active, but spitting out the star (in a way that makes it tangible) will make the loading zone active again. Funnily enough hitting the switch again will give you a view of the star flying off into infinity!
So far I've only done this glitch in CCM, but it should also work in SSL, maybe DDD if shells co-operate, and would technically work in RR if you lured a fly guy all the way to the top of the big house :P
Going to end this post with one final cool thing I achieved. I first did the moving with a star glitch with the Lil' Penguin Lost star. Then I collected the 100 coin star, with the other star still in my mouth. When entering the course I was at 3 stars, and the 100 coin star set the total to 4. Then when I said yes to saving, the other star came out my mouth and I started collecting it... as I was saving. This increased my total to 5, and resetting at this point counted my file as having 5 stars! The save from the 100 coin star counted the star I had collected while the game was saving.
