Hi mikael,
this behaviour occurred in new games (I tried both large and medium-sized maps). I actually never player a given game for more than ~1h (in summary). The first time this occurred, I was in the middle of completing the tutorial explaining how to establish a bus line. After that, the same game froze whilst playing through the second tutorial.
BTW: I also noticed a significant drop in allocated memory for the game’s process when the last freeze happened (down to some ~20MiB – before that it was more in the region of ~200..300 MiB). There were 10+ GiB of free mem at all times and all of my 4/8 cpu cores were pretty much idling (the game’s process itself did also not consume any cpu time according to Task Mgr while the game was frozen – I can see this w/o minimizing the application, since I have Task Mgr opened on another monitor most of the time..)
Cheers,
Christian