Your Mac has slowed to a crawl, with spinning beachballs and a juddery interface. You open Activity Monitor and read this.
kernel_task
Your Mac goes all sluggish, you open Activity Monitor, and there at the top of the CPU list is kernel_task, taking 100% or more. Why?
What should you do with a Mac whose fans keeping coming on full blast, with high CPU loads from kernel_task, and sluggish performance?
It’s hot, you’re hot, and your Mac has slowed right down. Activity Monitor tells you that it’s kernel_task which is to blame. Is macOS playing up, or what?
The Eclectic Light Company 