Limited by MainThread?

I really don’t understand why MSFS is indicating that I’m limited by MainThread. Sitting in a C172 at LOWI (ORBX) I get only 23 fps (MT 35-37 ms). Monitoring shows GPU @ 45 % (80 °C) and 16 Cores (HT on) mainly fluctuating between 15 and 40% (45-55 °C). I was monitoring quite some time but not one core came even close to 80% usage. I always thought that being limited by MT means that Core 0 pegging @95-100%. What am I missing?

I’ve seen related questions here and then in different threads but I’m not not aware of any clear answer. Maybe I’ve overseen something.

Probably depends on your settings. Some settings tax your CPU, while others tax your GPU.