Comment 21 for bug 387620

Weird that one thing is that is mentioned in several similar/related problems and is not mentioned here (and worked for me): use kernel boot parameters "acpi.power_nocheck=1 acpi_osi=linux".
Several previous kernels (from 1~2 years ago) don't have this problem in my notebook, so yes, it's a regression to me.
Sanal: you can control the throttling either with "CPUfrequency scaling monitor" panel applet or in the terminal (google for it), but I don't think it'll alleviate your problem just a little bit. I suggest you try the kernel parameters above.