After the gold thief trial, drop down to the wooden building underneath the guardian. There is a hidden entrance near the top left of the room, approximately over the middle bird painting. It puts you into a treasure room, but exiting the room puts you into the castle interior. My tests indicate that this can save about one second compared to the current route.
There is also a faster way to get to the third princess after the gold wizard trial. After going up the shaft lined with teal blocks, keep going up until you reach the open door that is above and slightly to the right of the shaft. The door almost lines up with the treasure chest that you would pass using the current route. The door puts you in a treasure room, but exiting the room puts you at a different door that is closer to the princess. My tests indicate that this saves about four seconds compared to the current route.
I can post videos if the explanations are not clear enough.
I also know about the room you are talking about I found it a few years back and thought that the same door was taking me to 2 different rooms everytime I went in, Didn't realize until somebody on GFaq's pointed out that it was actually 4 rooms that cycled through eachother. It's just the 2 doors that lead inside both have similar style environments around them.
