This new version uses a perfect 101 blocks, renders 25 times more squares at twice the speed and is just smarter it renders 250000 squares per seccond for me. Just multiply 5000 by by your average fps. It might seem slow but most of the time is spent genrerating random numbers and adding things to lists for the squares, not rendering.
lol almost 2x faster on turbowarp Check out my older version here: https://scratch.mit.edu/projects/1289830533/ My old version would draw lines to make squares but now i just stamp them. A little less controll but its much better with speed.