iMac CPU 350%, iMac glacially SLOW

After months of dealing with this problem, I finally got it fixed!

While searching for a solution, I've come across posts from many other people suffering from the same problem, so I hope that someone sees my post here and benefits from it.

Above, BobHarris mentioned overheating. My iMac's vents were 95% clean, but this got me thinking.

Very long story short, I downloaded an app called TG Pro. What it does is allow you to set your Mac's internal fans to come on at a lower temperature than they normally would.

I installed the app, pretty much using the default settings, and all of my Mac's problems DISAPPEARED. Gone, just like that. Months of suffering put to an end simply by launching an app.

I waited an entire day before posting this, just to make sure the problems were gone for good, and my iMac is still running better than it ever has before.

Now instead of my iMac choking if I use Firefox or Photoshop, I can run both simultaneously... and ALSO watch a 4k video, run MS Word, run Slack, and more, all at the same time... and Activity Monitor never goes above one or two bars!

I know this sounds like an ad, but I assure you, it's not. There are other apps that do the same thing, such as iStat Menus and Macs Fan Control.

After months of trying to get this problem fixed, I can't believe the solution was so simple!

Thanks for your response, BobHarris.

As mentioned in my post above, the temperature of my iMac at the time of these occurrences was between 64°c and 76°c - is that hot enough to cause such problems?

Also, there are times when kernel_task is not the problem. About a third of the times, it doesn't show up in Activity Monitor at all...

Sometimes it's kernel_task. Other times it's mds_stores. And other times, it's WindowServer.

That said, I just gave the vents on my iMac a good cleaning, and will see if anything improves.