Civ IV Slow on Windows XP

So my dad let me borrow his copy of Civ IV: Complete Edition a couple of months ago, and I installed it on my 2006 HP running Windows XP. It ran at a good speed for a few weeks, and then all of a sudden it started running EXTREMELY slow, like if one of the leaders wanted to talk to me it would be about 45 seconds between hearing his theme music and actually seeing his face, and I couldn't do anything except wait during that time. It was frustrating. Today I played and it was REALLY slow again, but later it picked up, though it was still slower than it should have been. I don't know if the issue is my processor or what, but I don't think so since it worked fine on the exact same computer a few weeks ago. I have downloaded a lot of files since I last played Civ, though I deleted some unnecessary files to make up for it and it ran slow before I downloaded the files. Please help!!

Showing animated leaderheads is demanding for the computer and they are only loaded when they appear, not when the game is launched.

If you play on big maps, the accumulation of units and cities can make it much slower progressively. Several Mods are also more demanding than BtS.

This said, you might have a problem with the cooling system. You should try to take out the dust from it.

Another option is to lower the graphics settings.

that makes sense, I am playing on the largest map size available, and kind of late in the game. How do you lower the graphics settings or clean the cooling system tho?

Overall, it's probably just a question of relative power of your computer. Civ4 can easily need 4GB Ram, a good processor and a good graphical card of its own.

There is a graphic tab in the 'options' menu. When you launch the game, go to advanced menu first (or similar, I don't play in English).

You'd be surprized how a simple vacuum cleaning of the external gates of my 7-year old laptop made a miracle! For a desktop, you would have to open it - do it only if you know what you are doing. Usually, a computer with a heating problem is making a lot of noise.

But I remember having completely "burn out" my previous laptop with Civ4...

Thank you. I played it again yesterday and it worked just fine. It was practically the same speed as normal, after I lowered the graphics settings.

Time to start saving for a new computer... Civ4 is entirely worth it!

A few things:

Don't do other things than playing Civ with your computer (internet, whatever). In the Task Manager, you can even set the Priority of the game higher by right-clicking on the process.

It seems that just Alt-tabbing to Desktop and back to the game resets the priority of the game. It only works once per session, if it works.

Reboot your computer when you feel that the game is slowing down.