Mac OS Big Sur | kernal_task usage is 500% when connected to external monitor I'm facing a system lag issue whenever I connect to my external monitor, even though there is no user process.
I have already gone through some of the answers in the stack exchange and did two things as of now.

I have disabled the automatic graphics switching.
I have disabled &quot;Display have separate space&quot;
There is no software update pending

as mentioned in this link CPU usage is too high with Yosemite and an external monitor
But the problem, even after those two changes I can see kernal_task is more than 500% and I'm not able to use Macbook pro at all.
Previously it was once or twice an occurrence, now it is happening every time I connect to an external monitor.

Activity Monitor


I have also taken a spin-dump ( 5MB ) and system diagnostics ( 200+ MB ). So I dunno how to share this here. Let me know if any of you need it for analysis.
This may officially seem like the strangest answer ever, but have you tried using the ThunderBolt ports on the right hand side of the MacBook Pro?
As per this blog post, the thermal sensor in the MacBook Pro is located unhealthily close to the left hand side ThunderBolt ports, which will heat up and trip thermal throttling (the kernel_task spike you see), thus seriously hurting your user experience.