Leviathan will probably only be a problem later. I take it you haven't seen either of my posted boss battles from before. Of course, I didn't explicitly say what they were, either, so I will only blame myself.
http://www.kraftfam.org/~erk/nesvideos/gigammz.zip
It contains a few movie files. One is a tool-assisted battle against Leviathan that I did using just the buster and the saber in weapon mode A. To summarize it, the ground level the first time you fight her is just right for serious pwnage, allowing you to lay a final hit into her shortly after she begins her ice-dropping, height-gaining attack. If anything your battle with her could be faster. The second round doesn't look as promising, though.
It also contains a battle against Harpuia. Don't need the ice chip to keep him down but it could speed up the battle a little.
The battle against the twin Flying X Drones is very fast and started way too late into the warning to be easily watched, but if anything you should be able to do it faster than that... and it's a really entertaining little movie.
The four-armed sword-wielding miniboss can clearly be better optimized. Mostly just forcing him to jump towards the back of the room better. This movie as well as the disappearing block movie are pretty much just for fun.
The TriRod movie was how I measured the time it takes to get the triple rod. It could possibly be optimized a bit but probably by only a few frames. This movie is good enough for approximation purposes, anyways.
About my "run"...I'm tired of lack of progress, and since I'm not expecting to submit it anyways I'm just not going to get the triple rod nor the shield boomerang. If I'm going to submit anything I'll do a double pass through the game and use this first run as a timing guide.
However, if anybody else does a hard mode run and decides to get the rod+shield, I'm 95% sure you should sacrifice the Train Core battle to get the shield. I believe Anubis stands to gain MUCH more time from the shield than the train, especially since the train can be defeated before it can do its A+ Rank attack. The trick is to take advantage of the pistons to standing slash it. If you don't know what I mean, you can check out that part of my beta run.
http://www.kraftfam.org/~erk/nesvideos/mmz.zip
MMZ10 - Start of level
MMZ5 - Start of boss fight
Otherwise, I don't expect to post any more of the run unless I do something in the movie I feel needs pointing out. Or if somebody asks for more, but there's going to be better runs coming soon so there's no need, methinks.