Chrome analysis

To use the network throttler in Chrome:

Go to Control Panel > Hardware and Sound > Power Options: Check which Power Plan is currently selected . The Power Saver and Balanced modes will both throttle your CPU under different circumstances, in order to save power, lower temperatures, and reduce overall system noise.

Definitely, the most direct and root cause is: the system fails to dissipate heat fast enough . Whenever the CPU or GPU takes a lot of load, it will get hot and reach a point where the cooling solution in your system fails to cope with the heat generated. At this time, the thermal throttling will kick in.