For anybody interested. Although the plugin is depreciated it is still useful for 328P MCU based Arduinos.
By MCU standards the way the Arduino changes pin states is very slow. The plugin speeds it up.
Using the plugin was a compromise, I wanted to speed up the pin change but I didn’t want to use direct port mapping which would tie the sketch to specific types of Arduino (IE 328P based ones). Using the regular Arduino code with the plugin means extra speed on compatible Arduinos while still being able to run the code on almost all other types of Arduino.