@Nick A
As shown in the figure, I tested your newly released patched image on this fanless DIY heatsink dev board using a CPU benchmark tool, and the CPU performance is indeed heavily throttled!
With v0.6.1, I scored 2571, with average core temps around 75°C. However, with v0.6.4, the all-core score dropped to just 985, with temps hovering around 60°C. This is even significantly lower than the official system image (1700+).
I would really prefer a version without these patches; otherwise, the board's potential is being wasted. After all, sustained operation below 90°C is perfectly safe for this CPU.
The official release limits CPU performance to prevent high-temp instability and reduce support tickets, but your image doesn't need to impose these restrictions.