This occure especially when laying a track.
In my map, it works fine, till a certain point,
and now it could take 30sec and more depending on the lenght of the new track.
Do we have an idea where exactly this problem will occure,
i mean, fe after a total track lenght of 1000 miles fe,
or after 30 depots or after 100 years or after 20 trains or something.
There you don't have my map to play with,
i can maybe reference to the superbowl map,
there i had also the problem after some time, lenght of track or something.
For those of you that do have a much better system, more RAM will be probably a help here (i've got 750Mb). Do you also have problems at the end of superbowl? or isn't there a problem for you guys?

so that new map-makers could have somewhere a guidline or idea about that, this could help on deciding the mapsize, number of sources, or even amount of trains, or goods generated etc...