Sorry about the trouble. The speeds were set based on the processing speed of my computer. Since the game runs by constantly refreshing the window and feeding the information about the balls location to the code, having a computer that can process that information quick enough is important.
I'm glad you found a method that fixes the issue for you. I believe another fix would be in this line:
if (ball.xcor() >= (paddle3.xcor()-25) and ball.xcor() <= (paddle3.xcor()+25)) and (ball.ycor() >= (paddle3.ycor()-50) and ball.ycor() <= (paddle3.ycor()+50)):
If you change the number 25 to a greater value, say 50, the game should be able to account for slower processors.
I am not allowed to change the game for now by the rules of the game jam, but I will update it once the jam is over in about a week.
Thank you for the feedback!