This small patch allows you to easily change the player's speed on the overworld (hex editing isn't really an option, as many values cause glitches and none make the movement look as smooth as the original's). It's mostly a patch version of carol's "fast.asm" overworld sprite, except much less bloated.
With this patch you're limited to multiples of the SMW's original OW speed (you can only make it twice as fast, thrice as fast, etc.), and you won't be able to change the climbing speed individually (it will always be a little slower than the walking speed). Both should be sacrifices worth taking, though, and the latter can easily be changed by hex-editing $049415 (x21615) to the same value as $049414 (x21614).
Credit isn't needed, but if you desperately want to lengthen your credits list, credit carol instead.
I believe this patch to be the cause of the bug where a level name will not update sometimes when you move to a new tile, as the issue went away when I set the speed back to normal. This issue is only on bsnes/higan and consoles, it does not show up in snes9x.
EDIT: I found that increasing the multiple decreases the chance that the level name updates. x8 speed results in the name almost never updating, even if you reduce the base speed to compensate. I should also note I tested this on SA-1. It may work fine on non-SA1 roms.