I'm using Simutrans 102.2.2. Whenever i save my game the framerate slows down alot. It seems to speed up when i pause the game then unpause it. It doesn't happen when i load a game or anything.
Seems to be related to this bug report:
http://forum.simutrans.com/index.php?topic=4163.msg40390#msg40390
Could you please retest with a recent nightly?