How to fix MacBook Pro when you got 800% kernel_task CPU usage and slowed down

One day in June, my Mid-2015 MacBook Pro started to slow down. When I checked in Activity Monitor, kernel_task was maxing its CPU usage.

I've tried to:

• clear my HDD.
• Start in Safe Mode
• Reset PVRAM

Ref: How to Fix Your Mac’s “kernel_task” High CPU Usage Bug

Nothing worked or improved my Mac's performance.

I bought mine in the July of 2016. I've been using it for 3 years.
Perhaps, its time has come.

It was not true.

I found out the best solution.

• Turn on a AC.
• get a fan, place next to my MacBook Pro, turn it on, and point it to MBP.

That's it.

The summer season started. The temperature rises. I just needed to cool down my MBP.