MacBook Air extremely sluggish, unusable

Nov 19, 2018
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I have a 2011 Macbook air. I will list the problems that I am experiencing, though I do not know if any of them are related in any way.

First, the specs:

13-inch MacBook Air, Mid 2011

1.8 GHz Intel Core i7

4 GB 1333 MHz DDR3

Intel HD Graphics 3000 384 MB

OS: Mac OS X Lion 10.7.5

251 GB flash storage, of which 181.81 GB is free


1) Extremely sluggish: When booting normally, there is significant (1-2 second) lag when moving the mouse and clicking on anything (using either trackpad or external mouse. This lag, however, is solved when booting into safe mode by holding shift while booting. However, safe mode is not a complete solution (as sound is disabled, videos won't play etc.)

2) When booting normally, activity monitor marks a process called "kernel_task" to be using 300-400% of my CPU. In safe mode, the task is still present, but with a CPU usage of between 5-10%.

3) The battery no longer charges (and no longer works?). Computer must be plugged in at all times for it to work. Unplugging the magsafe causes the computer to immediately turn off. Curiously, under the battery menu, it says "No Batteries Available," but also "Power Source: Battery."
Sep 17, 2014
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OK, need to ask some questions:

1. Have you ever done any disk cleanup/maintenance/repairs, from a software perspective? You can actually do quite a lot of disk cleanup on your own, and there are some excellent products available (both free and commercial) that can help you with that.

2. Are you making backups to an external device? That task is so, so critical. If you are doing that, what software do you use for that task?

3. How much space is on your internal drive?

4. Do you use any third party (ie, non-Apple) programs? If so, which ones?

5. Have you ever thought about upgrading the Mac OS to one that is more recent?

6. Your battery issues sound like you need to have the battery replaced. You can replace it yourself, with guidance from this link:

Just make sure you purchase a genuine Apple battery. DO NOT use a third party one.

To confirm the battery is "bad/gone", download and run the excellent program coconutBattery, available from here:

Make sure you get V3.3.4, which is the one compatible with your OS.

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