WarashiIf your Mac's fans spin up, the bottom gets warm and kernel_task suddenly uses lots of CPU, your Mac is protecting itself from heat.
What kernel_task is doing
kernel_task is macOS itself. When the chip gets too hot, macOS makes kernel_task appear busy so other apps get less CPU time, and the chip cools down. It isn't the cause; it's the brake. Quitting it isn't possible, and isn't what you want.
Thermal throttling
Throttling means macOS lowers the chip's speed to stay within safe temperatures. On fanless MacBook Airs it happens sooner under long, heavy work like exports, builds or games; Macs with fans can usually sustain full speed longer.
What you can do
- Find the app that's actually working hard (sort by CPU and GPU), and pause or quit it.
- Keep vents clear; avoid soft surfaces under the Mac.
- For long heavy work on a MacBook Air, a cooler room or a stand helps.
- If it happens daily, consider whether your work needs a Mac with a fan.
Know how often it happens
Warashi records the minutes your Mac spent slowed down by heat. Its Mac running hot alert tells you when it starts, and the Upgrade Advisor counts throttled minutes per week when it recommends a chip.