Topic idea - how to optimize sketches for the P2D renderer

In one of your videos on youtube i learned that using the P2D renderer could improve performance in some applications. However, after trying it with one of my sketches (a random polygon generator with some basic physics added) and getting worse frame rate than with the standard renderer i realized that something in my code was not working properly with P2D. In the video "Coding Rainbow Live #46: Perlin Noise and Flow Fields" at about 2 hours and 26 minutes you change the processing renderer to use P2D and it still worked. How do you make sure your sketch works optimally with P2D?