Light build trouble

Hello everyone,

I have build a new computer with a ryzen 9 3950X 16 cores / 32 threads…building times are soo fast compare to my old i5 3570k ! (everyhting is so faster…)

When i build lights, CPU usage are near always at 100% :

Capture.PNG

However, i have one map where CPU usage are not too high, and build time slower than usual, even if the map is smaller and with less lights than the other ones :
Capture.PNG

World settings are default ones.

Maybe anyone have any idea ?

Thanks a lot !