I am sorry to come back so lately... Just fell asleep after all the day supporting this and other threads. Today I will be less active just to bring update release ASAP as promised.
ALL (and
kettyo in particular)
The way I'd recommend choosing 'vid_mem_usage' has changed after reading all the feedback. Basically, just try the following values in decreasing order: 180, 150, 120, 80, 60, 50, 40, 32 and stop at that one which causes no visual bugs / crashes.
Those who have 256Mb of video memory should start with 180 and normally should not get below 120.
Those who have 128Mb of video memory should start with 80 and normally should not get below 50.
Those who have 64Mb of video memory should start with 40 and normally should not get below 32.
Ignore AGP aperture size from now on... It causes more trouble and confusion as I see
kettyo
As I read on, you seem to have found your top performance spot. Good job!
pbgrhino
Well, just install the fix and try the above recommendation about 'vid_mem_usage'. With 256Mb of video memory value 180 is definitely a good start.
rcoutme
Well, if you have file extensions hidden, you'll see it just as "Harkonnen" in your files explorer window. When you double click it, a notepad should start and open it. There find strings 'vid_mem_usage = 80' and 'insane_mode = 1' - these are to be changed if at all. All the rest in these files are comments. Coming update will be automated in many aspects, so you might want just to wait a little.
Raggamuffin
Well, by now I don't know what to suggest... Probably AGP is off or probably I have already asked you. Please subscribe to releases info thread, and try it again when I release update for my fix. It will perform more tests automatically and suggest settings, probably it will solve your problem or at least tell what might be causing degraded performance.
polyphemus
Yes. Since you have only 256Mb of physical RAM, setting everything to low is a must here if you want to play large/huge worlds. Then set 'vid_mem_usage = 80', 'insane_mode = 1' (insane mode is also a must in this config if you want noticeable improvements, but you shouldn't alt-tab frequently from full-screen mode with it being set).
DeyofAlgiers
Yes, you made the right step by replacing 'zlib1.dll', otherwise patch would have no effect. Also you have extracted 'Harkonnen.ini' in the correct location, otherwise the patch would show you an error message. I recommend using 'vid_mem_usage = 80', 'insane_mode = 1' with your system. Make sure you have AGP turned on. Someone offered to turn it off long before my fix, but this time it might be the reason of slow-downs.
If you have AGP on or didn't change it (in this case it's still on as default), try settings 'insane_mode = 0'.
polyphemus
You may find your civilization 4 folder in "c:\program files\Sid Meriers' Civilization IV" or such. You may also search your hard-drives for 'civilization4.exe' and seek for locations like this one. Extract or copy both DLLs and Harkonnen.ini there. Make sure that 'zlib1.dll' becomes overwritten. So far, it should work for you. Settings like AA/textures/etc... you were asking about are located in game options. GAME_MAIN_MENU -> ADVANCED -> OPTIONS
Solver
Yes, you are right. I will describe current situation with poll in my next reply.
Merum
That's insane mode effects. If you have 1Gb of physical memory, switchching it off (insane_mode = 0) should solve black-screen-after-alt-tabbing problem without loss of performance.
Ginger_Ale
Well, thank you for trying anyway
The patch had to save ~50-100Mb of memory anyway. Though, video card weakness neglected all effects
Kilim
Phew, I'm happy for ya! Tenacity brings belief in success, belief in success brings the success itself
Cube4
Hmm... that's strange. Movie surfaces aren't affected by my fix. I will check zlib.net for fresh sources. AFAIR, I have downloaded the most recent source there. Also, there is a link at the bottom of post #1 to original 'zlib1.dll' file. And 'zlib1.dll' isn't connected to movies playback. Probably my patch has negative effects on intro movies in some cases, I will check it more closely. Thanks for pointng that out.
obe
ndvsky
Thank you!
Zydor
You are right... the sleep-of-the-dead started the day I released it
Anyway, I'd appreciate people to try various settings on their own. 'Harkonnen.ini' is as simple as a boot - just two things to change, with most effects coming from 'vid_mem_usage'.
Thanks to everyone who helped me by answering other people over here while I was away! This thing grows a little big for a single coder to maintain, especially with a lot of work still to do with the fix aside from supporting. I don't mean I give up replying everything and everyone, I just want to reward those who help me with that 
I do not see the ini file of which you speak... I thought it might be the Civ IV icon file, but when I try to open that, the game starts...
