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So, I did a Cinebench R23 benchmark just now (16", M1 Max, 64RAM), started with Low Power mode, ran it for 10:00:00 and the score was 10834, then, immediately, after this test, I ran it again, this time in High Power mode and **SHOCKER** it scored 12108.
Interesting! Can you try a 60 minute test and post the results?
PS - I should also add there are other components on the motherboard that can thermal throttle too, e.g. when the CPU demands more power to work and parts of the board have to start supplying that extra juice, so overall design has to be good to ensure those can dissipate heat.
Either way, "starts faster in full power mode then gets slower than when in low power mode" is a sure sign of thermal throttling somewhere in the machine. The decision is then whether it's faster to have it run at max capacity for a while and then swap to something slower than low power mode, or just having it all in low power mode from the beginning - short renders may complete before throttling occurs, for instance, so you can just do those in full power; but very long ones may benefit from just starting in low power mode for final overall render times.
The main, simple thing to take away here is that a CPU is NOT a uniform single thing - it has different parts that make it up. Different software will call upon those different parts to different amounts, and those different parts may result in different amounts of heat being generated. The example most commonly given is the AVX instruction set.
Not all software will call those different parts in the same way, so even though 2 different software says "100% being used", it may NOT mean the same parts are being used. Corona is very optimized for performance, and when it uses 100% that can indeed cause more heat than other software - but doing anything else would mean Corona would be slower, even before thermal throttling happened.
If Corona was poorly optimized, we'd not see the graphs and user reports where it runs faster FOR A WHILE than in low power mode, THEN runs slower. The only explanation for this is that the design could not dissipate the heat and it built up until the CPU decided to throttle itself. If Corona was poorly optimized, it would always run slower and that speed would be consistent and not change over time.
Thus, there is no way to "optimize" Corona here, only to "cripple" it to avoid so much heat being generated - and you can already do this yourself by setting Corona to use less threads, or by swapping to low power mode.
This will be my last post about this issue because is very difficult to explain here. More test must be done but not from us but from developers. Try to run a Cinema4D native render scene (not corona or Vray). You will able to reach the 995% of the CPU for hours and also you can place the MacBook on a pillow without any issue. You will find the same Cinebench of an iMac i9 10K generation.
Alex
I'm glad that you have finally read the explanations that we wrote multiple times on why the issue occurs with Corona and not with some other software and that finally the issue does not require any further comments.
The thing is, further investigation does not seem necessary. We can't say how the native renderers in C4D use threads, how optimized they are, etc. What we can say is that Corona and V-Ray are VERY good at using a CPU to its full capacity, and this seems to be the problem as the CPUs or some other element in the machine end up throttling. Since no program can ever "make the CPU do more than it can do" that comes down to the hardware not keeping everything below operating temperatures when the CPU is maxed out.
The only solution would be to deliberately make Corona and V-Ray NOT run at full power, which would be somewhat backward. Of course this should be possible for you to control at some level by reducing the number of threads Corona is allowed to use for rendering, which may keep temperatures down (EDIT - or of course use low power mode, which is the OS equivalent of reducing the power of the CPU available for use). But ultimately the tests are pointing toward the fact that the hardware does not keep the CPU (or some other element in the machine) cool enough to avoid throttling when the full power of the CPU is used for an extended period of time, and that one comes down to the hardware manufacturer.
Absorption is responsible for this effect so you can just create a crystal clear material and enable absorption with some dark/black color: https://support.chaos.com/hc/en-us/articles/4528339318289-What-are-the-two-available-SSS-modes-C4D
