I am not exactly sure if this issue still exists in standard, but it once did. So if it was fixed in the past, please let me know and move the thread.
When the list server is queried, e.g. when opening the "Play Online" dialogue, the game will be unresponsive until it either gets a response from the listserver or the action times out.
Same goes for querying a server, though it's not that bad here, as it will time out much faster.
Optimally the dialogue would open empty without these informations available, run the query in the background and update the dialogue as soon as the information is available.
I am aware that this is some kind of "in a perfect world" situation and likely needs a lot of changes in the code, so the easy solution would be to set a lower timeout. The current value feels like ages of unresponsivenes and will report as "simutrans is unresponsive" in some operating systems.
Is there any specific reason for that long timeout or can this be changed?