You might try to decrease the number of loops so that the program is a bit faster and more accurate also .Also you may consider to program each body with respect to other and then integrate all the other possibilities(This might not work ,I am not confident).

You might try to decrease the number of loops so that the program is a bit faster though it becomes less accurate also .Also you may consider to program each body with respect to other and then integrate all the other possibilities(This might not work ,I am not confident).