NinjaClick is a free easy and simple Open Source Auto Clicking application. Just change the text from 10 to any other number, and click the check mark, and the clicking time will change (NOTE: The smaller the number the faster the clicks) You can go to File/Start to start the app, or press F1, and F2 to stop.

NOTE: Make sure NinjaClick is open/selected so you can stop the auto clicking, when you press F2.