This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
There's no reason why executing a script from Runtime.exec() should be slow. How are you measuring the times? Do the commands within the script run slower, or is it slower to start up? What does the script do?