Why you need to know:
Signs that your Mac computer is running slow are problems such as applications taking longer than usual to close or having to force quit such applications as well as a longer waiting period as your computer boots up. Eventually, this will become an inconvenience so it's time run some simple maintenance checks on your device to restore it to its original speed and performance levels.
What you will need:
Mac computer plugged into the charging source.
Internet connection (and an e-mail account)
External hard drive/memory
How to get it done:
It is highly recommended that files are backed up on secondary storage media such as an external hard drive, SD memory or USB thumb drive prior to running these maintenance checks. If the computer is on, power off or restart while holding Command + letter 'S' to boot into Single User Mode. Single User Mode is especially important if the MAC runs on multi-user accounts to allow one user to run as a "super-user" and have access to the entire system. If you are new to MAC/Apple software but used to work on a Windows device, this will take you to a screen similar to what is known as Command Prompt.
The next step is to type in the following command to check the boot volume's file system, 'fsck -y' which will display another line of command when complete which then requires to run a mount of the boot volume with the command 'mount -uw/'. The boot volume may sound confusing but it is simply the area of the disk that contains the startup files and operating system files and mounting creates a physical location or partition to make a part of the computer's operating system accessible to the user running the maintenance check. This will let you know if the hard drive is ok (note that, if it detects that your hard drive has an error or is malfunctioning then this means you will have to change the hard drive or re-install the operating system.
To complete the maintenance check, you must run the command to fix the ACLs, that is, the access control list - a series of permissions that is attached to an object in the operating system and defines which users or system processes are granted access. Now, MAC users will debate but ACLs are similar to that of the registry of Windows computers. The command used is 'chmod -R -N /Volumes' (please note the spaces in between each character to input the correct command); this will clear the errors. Nevertheless, there is a fix recently put out by MAC (downloadable) which actually fixes the errors instead of removing them.
The next chain of command is to reboot. Type 'reboot'. Now, the computer should startup or boot faster and run at a normal performance level.
Helpful links: http://james.brooks.so/blog/fixing-slow-osx-startup/Information written and compiled by Kareem LaTouche and Stephanie Lyew