I didn't expect a time this low to be possible without a glitch in the overworld! But now I see that sub-50 is possible, though this run is so clean that it will be quite difficult. The fast death in the last room and then jumping up right away is really tricky to get right, and luckily this run came on one where the three turns and the lava section were particularly tight. I guess there are three ways get sub-50:
1) repeat this run, but find a total of 6 frames to shave (e.g. the second intentional death could be improved). This seems really hard and annoying because it would require resetting on even the slightest error (e.g. a suboptimal overworld turnaround)
2) don't hop at all after performing the glitch. I find this to be really hard to pull off, but it could be learned.
3) Find a way to perform a glitch in the overworld more reliably, and add that to the run.
If/when I try to beat this run, I'm going to try option 3...