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.