Hi Pete,
thank you for investigating this as it is indeed really intriging.
Let met repeat my scenario with FSUIPC enabled (and excuse my poor English):
. start P3D v3.1 with default start scenario
. Start scenario window appears in less than 10 seconds
. Click OK to launch the flight. Window "loading terrain" appears for less than 10 seconds and P3D is then ready to fly.
. Click on menu option and change the time to system time and click OK
. Windows "loading terrain data" appears and stays there for 10 minutes with CPU at 100%, before showing the Aircraft on the runway again.
Strange is that doing the same scenario without FSUIPC4 enabled, the second loading takes again 10 seconds.
In the log,you will see the time when the 2nd loading finishes :
19157 Advanced Weather Interface enabled
640166 Sim Stopped
...
(Yes, for the time being, I've disabled the loading of FSUIPC).
I'll be away today till the 20/1 and will not be able to use the sim, but will check your posts.
Again, thanks a lot Pete.
Patrick O