This movie is 8 frames faster than Induviel's userfile upload in pure input and 16 frames faster in reaching the goal thanks to better lag management and speed control—which are mostly the same thing in this "game" because it lags when you move slower or faster than it wants you to and is extremely picky about it.
It is further improvable if you find out a better lag management strategy and/or lengthen the input to make the character reach the goal sooner. I'm not going to submit this unless I solve the extra frames of lag in the last section or find a way to move at >10 px/f (which is technically possible) at will; feel free to use the movie as a reference for your own attempt. The horizontal subpixel speed address is
$86F0. Sub-880 feels doable.