El Justo,
First of all, great scenario. I don't generally write "fan letters", but I must say that this is an excellent scenario.
Secondly, providing that you aren't pulling my proverbial leg, I will explain my "secret".
To begin with, I tweaked my system for performance using a commercial tweaker. This is because the system is ancient and very, very low end (compared to the currently available systems). The tweaking elevated my system performance enormously and the few things that I do only squeeze the last few drops of performance from the system. In other words, because it is running about as fast as it can go, the things I do only add a little bit to the system's overall performance, but for me that little bit is essential. Since my system is connected via dial up, I can shutdown a few things that someone with a broadband (or "always on") connection might not consider or be able to terminate (due to security concerns). For example, I will routinely shutdown my antivirus program and my firewall. Doing that with an "always on" connection is just inviting trouble.
Having said that, here's what I do:
1. shutdown every program not essential to make XP work.
2. shutdown every service not essential for XP to run (except windows audio).
3. start my memory manager/memory defragmenter.
4. defrag the memory to maximize the amount of RAM available.
5. repeat step 4 to make sure you got it all (the RAM that is).
6. Start Civ, load TCW, and play.
The memory manger I run will, from time to time, recover unused memory resulting in a slight slowdown in the game, but it only lasts for a minute or two and everything is back to normal. Other than these things, I don't do anything else. Being perfectly honest, the system does things that it probably shouldn't be able to do in terms of performance (given its age, the hardware, etc.) and I really don't know how to account for it except to say that I guess I am just lucky that way.
Oh, and I hope your "Iggles" win on Sunday! (I am an embarassed and disappointed "Stillers" fan)