It clearly says limited by main thread which is the most common limiting factor unless you’re running in 4k+ or VR.
Overall CPU utilization and power consumption is not a good indicator.
You have the main thread runnig at 100%. If your CPU has 16 threads then the overall utilization will be 100%/16=6%. But that doesn’t mean it can run any faster.
As any sim this game requires as much single thread performance as it can get. That’s why the X3D CPU’s and high frequency desktop ones perform the best. It’ll never run great on a laptop or a console (which is basically a gaming laptop without a screen).
They might optimize some more to spread the load into multiple threads, but I suppose it’s already optimized to almost the limit.
There are certain things in a sim you need to do in a sequence and can’t parallelize.
What you definitely can do to lower the CPU load is turn off all air traffic, boats, cars etc. and in-game multiplayer. Also avoid PG scenery and hand crafted airports.