If someone were to hack the game, in addition to fixing the slowdown issues it would be nice if they could fix the two most annoying aspects of Double Dragon; namely the accidental headbutt and the accidental picking up of weapons on the ground if you are standing over one and you do an elbow smash.
There are so many accidental headbutts in that game because it counts your holding the joystick to the right or left as the first input no matter how long you have been holding to the left or right. For example, you can be walking along for several seconds, stop and then try to start walking again quickly and your character does a headbutt. It shouldn't be that way. It should only do a headbutt if you have done a real "double tap" on the joystick, i.e. stop, then tap quickly two times to the left or right.
It tries to pick up weapons when you are doing elbow smashes because the punch button is used in combination with another button to do the move. It should recognize that when you are pressing the two buttons together, you are not trying to pick up a weapon; you are trying to do an elbow smash.