I found a solution!
Death Mountain is finished!
43 frames faster!
http://tasvideos.org/userfiles/info/31889946277063253
The winning solution:
-I saved time fighting the first orange daira. After the first whirlwind attack, I walked through it and did the second whirlwind from the right side. Doing so killed it 6 frames faster. That gave me the 4 frames I needed to skip another 21-frame cycle on the death screen.
Ideas that failed, for those who like to read:
-I tried the red daira idea first, but, indeed, the only way to make it work was to not get the 100 XP. It doesn't throw a projectile axe until it also has a fully extended hand-axe, and the hand-axe has a longer reach than Link's sword. I could still make a kill after it releases the projectile axe with movement skills, but the projectile hits only a few frames later.
-I would bypass the first orange daira, intending to kill it on the way back. This way would save a 21-frame cycle, but then I assumed it would take at least 27 frames to kill it. Even if it were only 21, it wouldn't save time.
-I went back to the laggy room with the octoroks and goriya. I tried every way to get a swordbeam on the third octorok, but there was no way. Note: The goriya lag frames ultimately did not result in any time loss, nor did the 1 frame I had to wait to manipulate a bot's position, because of the 21-frame cycle.
-I tried delaying the level up (184 frames) and changing nothing else. I still needed 4 frames, and so I think that time in the menu doesn't count toward the cycle.
-I considered getting another 50-bag + 20 XP so I wouldn't have to fight the orange daira. I would have needed to change a lot of things, and it probably wouldn't work anyway. I also considered the 'nuclear option' of not getting Attack 2, but that looked like it would fail long-term.