The performance of the Extrudalizer script, like many other powerful design tools, can be significantly impacted by the complexity of the shapes and faces being created. As the number of shapes and faces increases, the script requires more processing power and memory to display the 3D Extrudalizations, which can lead to a decrease in the on-screen performance. It is crucial to understand how complex shapes influence the script's performance and learn strategies to manage these complexities for an optimal user experience.