Apparently, this is due to the CPU throttling that kernel_task in Mac OS operates to prevent heat from damaging the hardware. Some research on the web confirmed my suspicions that there was indeed a relation between the temperatures, always high but strangely never above 90-92C, and the general slowness, in particular with tasks such as video encoding or heavy testing.

For example, Handbrake video encoding tasks were ridiculously slower than I’d expect from this sort of machine, and then I also noticed that the kernel_task process was almost constantly at the top of my activity monitor with 200-300% CPU utilisation. Then I also noticed that with no doubt the excessive heat was affecting the performance of the laptop quite badly, much more so than I’d have thought possible considering that the temperatures were anyway always well within the 105C max, so from that point of view the CPU was still operating “safely” lately, however, the laptop seemed to be performing like a much older machine… which was no good. I had already tried the usual stuff like resetting the SMC, or the PRAM/NVRAM, with poor results. That was until I got really tired of the noisy fans (always running at the max speed of 6K RPM), and I started to wonder whether I should bring it in. The CPU is rated to work just fine at a temperature of up to 105C, so until recently I didn’t really care too much about the temperatures since, after all, the Mac seemed to work fairly OK and I didn’t have any other problems with it. The laptop got really, really hot at times to the point that touching it for more than a couple of seconds was often more likely painful than just uncomfortable. Since I purchased it, however, it has always been plagued with excessive heat issues: even 85C in idle or with very, very light load! If I said that I could perhaps fry an egg on its surface at times, I don’t think I would be too far from the truth. It’s a thing of beauty and I love it, as I have the previous Macs I’ve had the pleasure to work with both at home and at work. I also have a better performing Hackintosh at home, but because of the portability I find myself using the MBP more.

My main machine these days is a mid-2010 15″ Macbook Pro powered by a dual core i5 (2.53GHz) CPU. Why would you want to reapply thermal paste on a MacBook Pro? A little story.

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