In my pretty unscientific testing, I saw ECO mode have zero impact on single core workloads and ~4% on multicore with a big drop in cpu temperature.
If I am reading the “Gaming CPU” chart correctly from your link, the AMD 170w performance was 114.8 FPS, but the 105w ECO performance was 111.4 FPS. Effectively nothing for a huge drop in power.
With makes sense to me. We have seemingly run out of cheap architectural wins. CPUs and GPUs keep cheating by amping up the power draw to improve the performance numbers for vanishingly small returns. To get an extra 5% performance on these chips can require 10s of watts.
It depends on the test. In that link I posted, 3dmark’s cpu test shows eco mode drop the score from 19000 to 14000. Which I guess is more like a 25% perf drop. In other tests, performance increased in eco mode.
It seems like it depends a lot on the workload.
I'm not sure about intel chips, but amd's last couple generations of chips have an "eco mode" which underclocks the chip for you. You get about 85-100% of the performance while consuming 60% as much power. The chips probably last way longer like that too. NVidia's GPUs have similar options. 3090/4090 cards can have a totally reasonable power budget if you're happy to lose ~10% of your framerate.
Arstechnica added eco mode to their benchmarks:
https://arstechnica.com/gadgets/2023/03/ryzen-7950x3d-review...