Playing a town Toukay, trying to reach pop 2000 by year 30. Started lagging badly around pop 600-700, first time I have had bad lag that early. Got steadily worse until: pop passed 1000, then magically, the lag disappeared. And I mean, totally gone. It's like a brand new game. I've never had this happen before, and I don't know what to make of it.
What operating system are you running? How many cores do you have?
It is possible, I suppose, that some background task like the MS Indexer completed its pass, and coincidentally terminated freeing up at least one core.
This game uses some rather nice multitasking, but if it is blocked it can be slow. It really sounds like an operating system event of some kind.
Running Windows 7 with a 4 core processor.
The lag had been going on for a few days, lately I have not been able to do more than a few months at a go. I was thinking the disappearance of lag was tied to some game process rather than to something else that was happening on my machine. Is it possible that the pathfinding would work differently when pop reaches a certain level? Or maybe the home/workplace optimization function?
I can't really say since I don't have a copy of the code, but what you describe has more operating system symptoms. As an experiment you could try turning the MS File Indexer off. It runs most of the time and is a processor hog.
I have to second the idea that the MS Indexer is a drain on processor time, although it's supposed to run in the background. From what you said about the lag lasting several days, I would add that there are several things Windows users generally have running that can take a long time to complete: the obvious ones being Indexer (which is on by default) and anti-virus software -- both of these will resume where they left off when the computer starts again.
You can easily control what Windows runs as Services by simply shutting down (disabling) those you consider unnecessary. Have a care with this as some of them are truly useful at preventing BSODs.
I haven't run Windows in years now, but I used to turn off most of the nanny stuff. I've been in computers since the early 1960s and don't normally need to be protected from myself. The problem with Windows is its external vulnerabilities and Microsoft's attitude towards its end users. They'd be better off getting rid of the NT kernel, but they are "too far boltered in blood to go back than go o'er". A new kernel would give many hackers a jolt out of their comfortable pew. They need something bullet proof and public domain like the Multics kernel. Secret source is just a red cape to the hacking bull.
How do you turn off MS File Indexer? This sounds promising. :)
It has been a long time since I've run Windows (XP). If I remember correctly you can enter the Services control system from the My Computer icon. You then find the line in the services list and simply mark it disabled. Then boot your machine.
This probably requires you to be an administration user with full privileges and you may have to enter using a console command these days. MS generally doesn't want people fooling with the services list. Daddy knows best, you know.
If all else fails, try the Help system under Services.