how to clean your hard drive? computer is running slow during start-up and loading applications

An application like OnyX, available at http://www.titanium.free.fr/download.php . Run the tasks on the cleaning and maintenance tabs. With any disk maintenance software you should have a backup before using it.

This may offer additional ideas: http://www.thexlab.com/faqs/performance.html

Mac does the cleaning itself at night: daily, weekly, monthly, so normally there is no need for Onyx.

Make sure that you have at least 15% free on your HDD at all times:

backup and the remove very large files you do not need (like old VM's or so) and empty the trash;

one very large file you do not need is the sleepimage (which is as large as your ram):

open Terminal

copy/paste the two following lines

sudo pmset -a hibernatemode 0

sudo rm /var/vm/sleepimage

type "exit" and then quit Terminal.

Your mac has a lot more free space on the HDD and will stop and start much faster because the very large sleepimage file is not written at shutdown and not read at startup.

I have a macbook pro OS X El Captan Version 10.11.6 MacBook Pro (Retina. 13-inch, Early 2015) How do you make sure you have 15% free on my HDD? And what is sleepimage file? As you can see I am not to computer wise.

I am sure I have files on here that I don't need, but do not know what ones to trash.

Thank you.

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