Same here. 2012 Macbook Pro, 16GB Ram, SSD etc. Pretty sure the issue relates to thermal throttling. It's particularly bad when in clamshell mode, plugged into

Same here. 2012 Macbook Pro, 16GB Ram, SSD etc. Pretty sure the issue relates to thermal throttling. It's particularly bad when in clamshell mode, plugged into the Thunderbolt display. kernel_task CPU usage shoots up when CPU throttling kicks in. I suspect however GPU throttling also is affecting performance. At times the GUI just feels really slow and laggy. Seriously considering ditching OS X altogether.