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.