Playing with fire: dealing with slow hot Macs

“Many users complain of performance problems, often associated with their Mac’s cooling fans coming on, sluggish response, and, if they look in Activity Monitor, very high CPU use by kernel_task,” Howard Oakley writes for Eclectic Light Company. “There’s a lot of conflicting advice as to how best to tackle this: last week I explained how kernel_task is a symptom of the underlying problem, and not its cause.”

“Bear in mind that any runaway process(es) can start to take over the CPU and result in a rising thermal load, which may trigger kernel_task to be used to lock those processes out and allow the CPU to cool,” Oakley writes. “These include old favourites such as the Spotlight metadata demon mdworker, and plenty of extensions, startup items, etc. They can be tricky to identify without taking a look in the log, where they usually leave a trail of distress messages and good clues as to what is wrong.”

Oakley writes, “My two best suggestions for dealing with high kernel_task loads and fans running at full speed are to reset the SMC, and to clean out your Mac’s fans and cooling ducts.”

Read more in the full article here.

MacDailyNews Take: For older Macs that run hot, a little vacuuming can work wonders!


  1. Follow-up PSA for MDN Take: Vacuuming out any electronic is not recommended as it can create static electricity and possibly damage the device. Low risk, but not a good idea. Using compressed air is the best way to get the dust bunnies out of a computer.

  2. I run software that tells my older MacBook Pro to turn on the fan sooner whenever the power is plugged in. Just an abundance of caution.
    I don’t mind the fan being on whenever it is not running on battery.

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