CPU usage time is below real time

Dear G4,

I am doing some basic calculations to test the new I9-13900HX CPU with GEANT4.
I have tried in multithread and monothread and I get similar behavior. I am not using the viewer.
The real time of calculation is always above the CPU time of calculation as you can see below for 1 thread:

  Number of events processed : 500
  User=37.047000s Real=236.042703s Sys=0.281000s [Cpu=15.8%]

It is like if the CPU is not used in totality because the USER time (understand CPU calculation time) is 37 sec while the real time to execute the calculation is 236 sec. I have checked that this time does not include the initialization but only the run time.

I do not understand this behavior. Do you have any hint ?

How much I/O is being done here, and what filesystem is output being written to? Based on this answer here: unix - What do 'real', 'user' and 'sys' mean in the output of time(1)? - Stack Overflow, it’s likely the application is I/O bound.

Thank you @bmorgan for your response. I do not write/read anything in this example. However, I have done some tests and it seems to come from WSL.
When using WSL1, I use less than 100 % of my CPU.
When using WSL2, I use the full CPU.
In both cases, the simulation time is similar.
I suspect it is just an erroneous text but at the end, the CPU is used correctly. I will do additional tests to confirm this