In fact, you won’t find any disk defragmenter built in Mac that running any version of OS X later than 10.2, because it does not need. OS X writes small files in one batch, eliminating a lot of the need to defrag a Mac regularly. Besides, many modern Macs ship with SSD, or Flash Storage drives, which don’t ever need to be defragged in general—they have their own maintenance process known as TRIM.

However, when updates, upgrades, installation or reinstallation take place, you might need to defragment it once in few years. It is when your hard drive has less than 10% free space that you really need to defrag your Mac’s hard drive. Fortunately, OS X has its own built-in safeguards that you could take advantage of them.

Step 1 Remove large files

Reducing big files like movies and other video files could make your drive boot smoother. Boot drive actually takes up more 80% of the total disk capacity that does nothing at all. Doing so also accelerates performance.

Step 2 Clone boot drive

This is a bit complicated to operate for averaged Mac users. Please remember that you do not have to defrag your Mac hard drive unless you have a sound reason to.

1. Prepare a blank fresh external drive to clone the boot drive of your Mac OS X.

2. Press option/alt key down to reboot your system.

3. When you use clone to boot, please erase the internal boot partition or the complete drive by using the Disk Utility.

4. Once you are done with the previous step, clone your external partition onto the internal partition.

Meanwhile, you got a bootable backup data.

If you find the given steps do not work very well and the slow performance is still there, it might be the reason of RAM space scarcity or un-updated OS X version.