Is there a defrag program for free that works?

hi all i have windows 7 and i was wondering is there a stand alone defrag program for free that does actually work and thats better than the standard one you get with windows 7 i can asure you my pc is kept sqweeky clean and even though ive ran the windows defrag its still slow at starting up and shutting down although its not bad once its up and running please help with the defrag