Add projects that are made to generate lag. Of course, there's more to it then this.
Research on lag here: https://scratch.mit.edu/studios/5339960/
Takeout lag here: https://scratch.mit.edu/studios/5339972/
And of course, we can't forget the Lag Licky: https://scratch.mit.edu/studios/5339993/
Scratch is a project of the Lifelong Kindergarten Group at the MIT Media Lab