I'm using an iMac (late 2015) with an Intel core i7 (quad core) 4GHz CPU with 32GB ram and a 3TB Fusion Drive. I'm a software developer working on a huge codebase that used to take about 30 minutes to build and run unit tests on my beast of a machine. Of course, running the build meant that the CPU usage was up through the roof and the fan working at its fastest speed.
I upgraded to macOS sierra yesterday, and my first attempt to build the project I'm working on took three and a half hours! During this time my computer and fan were as quiet as a sleeping baby.
I did some investigation and found that whenever a process uses too much CPU power to the extent of making the fans audible, in just a couple of seconds I see the CPU usage of this process falling down, and after a few minutes, the fan sound goes down too. It seems that in Sierra a feature was added to make sure that the CPU doesn't overheat by throttling the processor usage for high CPU demand processes automatically.
What I need to know is how to disable/configure this feature, because it's killing my productivity. I really love the other great features in Sierra, but I would certainly downgrade if there is no way to disable this auto-throttling.