Why is my Mac Book Air running so slow

To help determine the possible causes of this behaviour read the following. None of what follows is intended to fix anything, but it will provide the additional information required to advance troubleshooting.

There are three separate parts to it; please read everything and reply with the results of each part.

Part 1

Apple Support Communities contributor etresoft wrote a very useful app to quickly gather certain system information that may help point to a cause of this problem. Read about it here. It contains a link to download EtreCheck. Don't download it from anywhere else (such as may be found by following the results of an Internet search).

Copy and paste its output in a reply.

Do not be concerned about anything that says "Problem" or “failed” or anything else that may appear in red.

EtreCheck was designed to remove any personal information (such as your computer's name and serial numbers) but if you see anything that looks like an email address or any other personal information that should not be divulged to others, please delete or obscure that information when you post the reply.

When you are finished with EtreCheck, quit the program. It occupies very little space, and you can keep it or drag it to the Trash as you wish.

Part 2

Please determine if the problems also occur in "Safe Mode":

• Safe Mode or "Safe Boot" is a troubleshooting mode that bypasses all third party system extensions and loads only required system components. Read about it: Starting up in Safe Mode
• You must disable FileVault before you can start your Mac in Safe Mode.
• Starting your Mac in Safe Mode will take longer than usual, graphics will not render smoothly, audio is disabled on some Macs, and some programs (iTunes for example) may not work at all.
• Merely starting your Mac in Safe Mode is not intended to resolve the problem, it's to observe its performance without certain additional components.
• To end Safe Mode restart your Mac normally. Shutdown will take longer as well.

Part 3

System performance problems for reasons that cannot be isolated to any other cause justify an SMC reset. Be sure to read the procedure carefully and follow all the steps exactly as written, even if they seem inapplicable or trivial.

Please describe the problem in as much relevant detail as possible. The better your description, the better the chance of a solution.

For example, if the computer is slow, which specific actions are slow? Is it slow all the time, or only sometimes? When did it start to be slow? Did you change anything just before it started? Have you seen any alerts or error messages? Have you done anything to try to fix it? Most importantly, do you have a current backup of all data? If the answer to the last question is "no," back up now. Ask if you need guidance. Do nothing else until you have a backup.