File IO is slow. Depending on the sound, event.playSound() has to load in and decode the sound which takes time. For short sounds it can be more timely to play than audio.play() on Android. But it’s still a file operation going on.
Next on loadsave, you only need to load the file once at the start of the app running. After that, the table should remain in memory. You update the table and then save whenever you change it. You may have to do some techniques to get the table visible to all of your scenes.
But generally, if you’re in a tight, performance hungry part of your code, delay the save for a while. Updating the high score isn’t a critical operation.
Rob