@anybody Is there a way to make a quicker change than what the sequence editor allows? It seems to be in 16 millisecond increments, but I have an idea that will only work if the increments can vary.
Those increments are defined by the speed of the NES audio engine. The defaults are 60Hz (16ms) for NTSC and 50Hz (20ms) for PAL, but you can specify a custom engine speed if you really need to (in the Tracker menu). It'll still sound mostly the same, the timing just won't be 100.0% true to what the actual hardware can produce.
Also: a MMC5 version of the same tune, by w7n_mariohacker
Using the word "overclocked" is incorrect as it implies you are doing something with the clock. What's happening is simply that you're using some other process that is NOT waiting around for an NTSC/PAL VBlank NMI to generate your engine interrupts and are using some other process.
In fact, the Famitracker driver itself doesn't actually use NTSC or else it'd play at 60.1 frames/second. FT plays at exactly 60 so it's already using some other process and using the custom engine slider is just altering that process.