Run time with GUI


I hope that this could be the right section to post this question.

I noticed that the run time for the same simulation (same primary particles, same geometry, same number of events etc…) runned with command line interface or with Qt GUI interface are very different.

In particular, a simulation of 10 k events:
Command line: 0.3 s user / 0.3 s real
Qt GUI: 2 s user / 12 s real

Plese note that the storing of trajectory is disabled (/tracking/storeTrajectory 0) when the simulation is performed with the Qt GUI.
If I disable the visualization system (/vis/disable) I gain about a factor 2-3 but the run time is still very high.

Is that normal? Why the run time is much higher with the GUI if there is no visualization? (maybe I’m doing something wrong…)
And, why the real time is much higher than the user time with the Qt GUI?

Thank you for your help and explanations.


I found that with the visualization system disabled (/ vis / disable) the run time is consistent with the run time using the command-line interface.
The origin of the difference I initiallyobserved was to the fact that I tested the disabling of the visualization system in a simulation with a complicated geometry that affects the run time in a similar way to the visualization system.

I think that this almost answers my question, but why the visualization system affects the run time also if the visualization of the trajectories is disabled?
And what is the meaning of having a real time > user time?


From John Allison: