If you mean that the machine is taking long to boot, your problem may be a corrupt directory. If this is the case, I don't know of any freeware or cheap solution to this problem. I use DiskWarrior 4 and it works miracles in situations like this. If you don't have diskwarrior and you have a TimeMachine backup, I would completely wipe the drive with the "zero-out" security option to reallocate bad blocks on the drive and reinstall the system. This should clear things up. I don't work for Diskwarrior or it's parent company Allsoft, but I highly recommend this software to any Mac owner as this software is well worth it's hefty price tag. It's known to bring HDs and SSDs back from the dead.
Can you be more specific in what is taking ages to load?
You can run a basic apple hardware test on your mac (boot mac holding D) this would verify the major hardware components are fine, in my opinion it sounds either software based or hard drive related but i wouldn't confirm this without more information. If its taking ages to boot up and load the home screen; do you have lots of items on your desktop? Or do you have loads of startup items. (system preferences - accounts - your user - login items and delete everything in there then try a reboot.