Hey everyone, just wanted to let you all know that there is an 11-frame framerule in this game that dictates various long timers. I haven't seen this documented anywhere so I am assuming this wasn't previously known to the speedrunning community. What this means for the speedrun is that the game can only proceed to the next stage in intervals of 11 frames. Therefore, the barrel stage and the elevator stage can be played imperfectly and still take just as long as a perfect stage. Since timing stops when the final rivet has been removed from the rivet stage, every frame matters there for 1 Loop speedruns. However, it's worth noting that the cutscene of Donkey Kong falling after removing all rivets depends on the framerule, so only on the final rivet stage completed does each frame matter.

Zero page address $34 is the 11-frame framerule that controls all long timers. This address is decremented every frame and when it wraps around from $00 to $FF, it is forced back to $0A (10) and all long timers are decremented. The long timer that controls stage completion is zero page address $43. It's set to $8D once you reach Pauline and transitions to the next stage once the timer reaches $7A. With this knowledge, it's recommended to split when the black screen appears after completing a stage rather than the moment Mario reaches Pauline.

To give runners an idea of how quickly a level must be played to match the optimal framerule, I created a quick patch for the Revision 1 ROM that displays the numbers of frames remaining in the framerule when reaching Pauline; you can grab it from the Resources tab. Hope this thread proves useful for speedrunners of this game.