There are no defrag options for Mac OS.
Why not go to disk utility and verify your disk permissions - if errors are found - repair them, then restart your Macbook and see if that helps.
After you've done that and you feel that it's still slow - try doing a SMC RESET.
SMC RESET also fixes this:
The computer is running unusually slowly although it is not experiencing abnormally high CPU utilization.
Application icons may "bounce" in the Dock for an extended amount of time when launched.
Applications may not function correctly or may stop responding after being opened.
I aproximately heve the same problem of Viraj Toronto.
I'm running a Mac OSX ML on a late 2009 Macbook Pro 15".
I've been started to have problem (impressive prerformance slow down) 2 months ago, after a reboot from Windows partition to Mac ones...maybe it is just a concidence....
I already heve done the steps Linc Davis has suggested, but the results are good in terms of CPU%, System Memory, permissions and so on.
What do you suggest I can do to solve the problem?
PS: OS X Version 10.8.4, 2.53 GHz Intel core 2 Duo, 8 GB 1067 MHz DDR3, 220 GB for ML and 100 GB for Win7