When the Raspberry Pi 4 came out there was quite a fuss about how easily it had to throttle it’s cores due to heat under any sort of load. Throttling means it’s theoretical specs are not realized in the real world. The foundation issued several firmware fixes to address this over the past year.
Based on my experience this is still a major issue. The foundation is making the situation worse by some odd choices they took. First they don’t include a heat sink on the processor (or anywhere else). Having heard of the heat issues I ordered a heat sink with mine and installed it right away.
The second problem is the rather stupid decision they made to provide absolutely no ventilation in their official case. The top is completely solid. So they’re selling a CPU prone to overheating with no heat sink and no provision for passive ventilation in their case.
The very first app I ran (other than the installer and Chromium) resulted in a flashing thermometer on the display indicating the Pi was throttling. I removed the top from the case and felt the heat sink - it was hot enough to burn a finger. I removed the top from the case, exposing the heat sink to open air, and the throttling decreased significantly. Since this experience every time I have the top on and run something that stresses the CPU it throttles.
For comparison I have a Pi 3 B+ in the attic. In a case. In Texas. In the summers. And it doesn’t over heat.
I have a tiny fan I could use and to do something as suggested in this guide to install it in the case and implement automatic fan control. Of course in the vein of Murphy’s law this requires a 1 1/8” hole saw for my drill and the closest thing I have is a 1” hole saw. After measuring for myself I can tell that would hinder air flow from the fan. So I’d have to buy another bit in order to make this case work. Or for the same cost as the bit I can throw the official case away and buy a 3rd party case with ventilation slots and a built in fan. Hence my frustration with the decisions by the foundation.