Use nitsuja's build of snes9x found here:
Forum/Topics/1816
The one substantial difference from the previous run is that only mandatory battles are fought -- there is not one battle engaged in which is not required to complete the game. This strikes out the Shyster battles in Mushroom Kingdom (which saved approximately 5 minutes), and the Culex fight (which saved about 7 minutes). Consequentially, I was forced to restrategize the Mack fight (it is noticeably longer than before) and all fights after Nimbus Castle -- this is due to the lower levels and the absence of the Quartz Charm and Lazy Shell, both of which helped immensely in the previous run. Many of the lost time in these battles was cumulative in the end, probably losing me about 2 minutes total when compared to the published run.
A most noteworthy change from this run is the employment of the Power Blast item, bought with 5 Frog Coins from Tadpole Pond. Because of the deficit of Frog Coins come Exp.Booster time, I was forced to hold out until after Yaridovich before I could buy it (no huge loss there anyways). The Croco (both times), Punchinello, Johnny, Birdo, and Valentina fights are all faster (and maybe even Domino/Cloaker, but I didn't check).
The biggest loss of time was in the Smithy Factory fights, particularly the final area. I just couldn't find any better strategies what without the Quartz Charm and the strong Lazy Shell weapon. Thankfully the Power Blast kept me from wasting too much time otherwise. The 2nd Smithy Battle turned out well, since he held out rather long before even transforming the 1st. He also gratuitously transformed into Magic Head (unlike last time, where he remained Tank Head until Treasure Head) allowing me to deliver fast powerful hits (Magic Head has very bad physical defense) several times before changing into Treasure Head.
I'm a little disappointed, since I was hoping to break the 2:40 mark, and the Factory battles are a little unpleasant to watch compared to before. Still, I think the game can probably be beaten in under this time and unless there is some glitch no one is aware of, impossible to complete under 2:35 (just pulling it out of thin air...)