intel - Laptop CPU+GPU overheating after update to 18.04 LTS

I had this same issue in my last attempt to upgrade (with a clean install) from 16.04 LTS to 18.04 LTS. When I am browsing internet and specially when I am playing videos my CPU+GPU raises to fast to high levels causing throttling to fire and producing intolerable lags, leaving the system unusable for about 60 seconds or more.

With Ubuntu 16.04 LTS I never experienced this problem. Of course temperatures raised and throttling fired frequently (after all this is a laptop), but system was never unusable and video playback was smooth.

My previous solution was to downgrade to 16.04 LTS again, but now I need the newer version so I want to find a solution.

System specs:

• CPU: Intel Core i7-6500U


• GPU: Intel HD Graphics 520


• Ubuntu: 18.04 LTS


• Linux: 4.15.0-30


• Mesa: 18.0.5


• Hardware acceleration: on

UPDATE 1

Definitively it is a problem with frequency throttling. Instead of throttling CPU frequency to avoid overheating the procesor, the system is waiting until temperature reaches a limit (default of 85ºC) and then intel_powerclamp module fires, turning the system unusable for 60 seconds or more.

I would expect a progressive performance degradation from intel_powerclamp, but no, it is all or nothing. ¿Can this be configured?

My current solution is a modification of the script of this answer. It seems to work, but it is a big hack. There must be a conventional way to tweak system configuration to accomplish the same result.

UPDATE 2

If I turn off frequency turbo boost (echo "1" | sudo tee /sys/devices/system/cpu/intel_pstate/no_turbo) the problem completely disappears. Temperature never reaches the limit and the script introduced on update 1 nor intel_powerclamp fires and the laptop is smooth and usable.

Problem now is that turbo boost is disabled. With Ubuntu 16.04 LTS I never had this issue.

This is clearly a bad configuration of the thermal management subsystem of Ubuntu 18.04 LTS. Is there a way to fix it?

UPDATE 3

System is still unusable. Installing Ubuntu 18.04 LTS server and anything else than Gnome3 works. Well, it's not a novelty that Gnome sucks, but it was usable with 16.04...