Last weekend, my Macbok Air suffered a heart attack and I ended up doing several hard shutdowns due to an unresponsive system. In the end I had to do a full system restoration.
Everything is working fine now except for one thing: The CPU is slow. Much slower.
CPU related computing is much slower than before, even though I can't tell for sure how much exactly. When running Ubuntu, I monitor the clock speed and see that all four cores are running constantly at 0.8 GHz. The same is true for OS X when using the Intel Power Gadget. It used to be 1.8GHz to 2.6GHz. (Macbook Air 5-2, i5-3427U)
$ sudo modprobe msr ; sudo turbostat cor CPU %c0 GHz 11.50 0.80 0 0 13.34 0.80 0 2 7.76 0.80 1 1 18.47 0.80 1 3 6.44 0.80
Could this be a software related issue? What should I do then?
I guess you see that a hidden assumption is that the firmware is corrupted. This is why I tried to reinstall the latest firmware for my Mac from https://support.apple.com/kb/HT1237. But when I install that file I get the error: "This software is not supported on your system." Most probably because the latest firmware version is already installed.