https://beta.scratch.mit.edu/#262962679 User cs1158230 reported in the forums that the lag in this project was "kinda bad". Because they only posted a link to a non-shared remix, I don't know who wrote the original project. Here's the post: https://scratch.mit.edu/discuss/topic/321471/
I modified the project by adding a frame rate calculation and a counter to show the number of one second intervals where the frame rate was less than 24. This is arbitrary but the lag in intervals with a frame rate of 24 felt "kinda bad" to me (your mileage may vary). My computer Dell laptop (2009) Core t4400 @2.2GHz 4GB, Win10, FireFox 63.0.1 (64-bit) I played the game through level 10: Scratch 2.0 low frame rate count was 8 intervals Scratch 3.0 low frame rate count was 30 intervals