These are my two best speedruns for my game - https://scratch.mit.edu/projects/1255705427/ - 1. Reaching the "thanks for playing!" screen in 1 minute 24.8 seconds. 2. Obtaining all 12 hearts and falling into the void in 3 minutes 22.7 seconds! Think you can get it faster? Press the "." key to start your own replay, then save the project as a remix so we can see it!
The replay should be able to tell you if it desyncs. If it desyncs many times, try playing again with a different window size (ie, if you were watching in fullscreen, try watching without fullscreen). Please let me know if the replay works properly! I've verified that the replay works on Google Chrome on both my computer and my phone, but I don't expect it to work for everyone because Scratch can be very fickle sometimes! The game should be identical to the original version, except that I round the X and Y coordinates for the player (to the nearest 1/65536) so hopefully it's less likely to desync.