I have been doing tweaks to FS 2004 almost none stop since it came out.
Some already may know some of them some may not know all of them. Here are some of them.
In Bios I have found jumping your AGP Aperture size up to 512 MB. Do this if you have 512 mb of ram or a gig of ram or more. This will cause FS 2004 menu screens like aircraft selection and airport selection to appear slightly sticky. But once fs 2004 loads up and your sitting down on the runway you will notice a pretty big jump in framerates. 512 mb aperture might be to much try lowering it a bit if you get some major problems.
Another thing you can try after you just load fs 2004 and the splash screen comes up quickly press ctrl alt delete and click the process tab and end explorer.exe. After your done with fs 2004 to get your icon backs go back to the task manager and click file new task and type explorer and click ok.
Also for the ati or maybe even other graphic card folks. Move your AA down to 4X or or use the next to highest settings same thing with anistropic. If you max out your AA or anistropic things get either blurry or you cant tell much different going any higher and it just sucks frame rates done the toliet. Just turn vertical refresh off completely.
Also DEFRAG, DEFRAG, DEFRAG. Find a good registry cleaner and registry compactor.
Create a new user account call it flight sim. go to start settings control panel and click user accounts. Make sure the account has administrator rights. Now you can go and end just about every process thats on your system. So that nothing shows in the task tray. Also you can find on the internet what services are safe to disable on your computer. Read below
Basically make the flightsim profile a barebones strip down so nothing running in the background.Follow this url to create a hardware profile separate from your orginal configration so you can have no fear ending processes. This article will also describe how you turn off the process for that particular hardware profile.
to find out what processes are safe to turn off read this article
Also allot of people have jerky graphics or people have quick framerate drops from like example 90fps to 30 fps and back up. The reason behind this is. The amount of activity on broadband connections causes the system activity go like crazy. Even though your not accessing anything. just go to start settings network connection.
right mouse click on the network you are using. Click tcp/ip protocol click properties. Now click use the following ip address. Now you will see the enter inputs light up. now go to start run type cmd. Then type ipconfig /all Now type all that info into the input boxes including the dns info. By doing this will allow your interent to not constantly search for new ip information.
If you still get choppy graphics or want a framerate jump go back to start settings network connection right mouse click on your connection and click disable.
Also if you have 2 hard drives or 3 hard drives. Running all these harddrives can actually slow fs 2004 down. Its better to turn them off you have two ways of doing this. Right mouse click somewhere blank on your desktop. click screen saver then click the power button. Then select turn off hard disk after 3 mins. Click ok and all if you wait 5 minutes you should hear your hard disk click off. You will hear a loud clicking noise. If you dont they havent turn off. If you still dont hear anything restart and then wait about 10 min still nothing. Then something is running that is using those drives. you must find out what it is and turn it off. Go through your services and startup etc. If all else fails. Just go inside the box and unplug the power cords to the drives. This will either finally turn the drives off or will come up with and error as to what was running from those drives so you know whats needed to be disabled in order to turn your hard drives off via the power off screen. Once the drives are off you will notice a huge jump in speed.
Make sure indexing is turn off on all drives. right mouse click the drives in my computer to do this.
Turn your terrain mesh complexity all the way to 0 or 20. Do this if you know where you are flying is very flat. Turn the water detail to none if your above 33,000 feet or flying in and area where their is no water hardly. Select just land detail only if thats mostly what your flying over. turn off dynamic scenery unless you need it. Set all autogen stuff to just normal or dense. Anything higher then normal is really unrealistic especially in rural areas. Target framerate everbody says set to unlimited. This causes things to go to like 50 fps down to 10 fps. If you machine stays at contastly between 50 fps to 30 fps you wont notice any jerking. If you see 50 fps down to 10 fps this will cause jerking. Look at the high and low of your frame rates pick a target framerate somewhere in the middle. If the jerkyness is really bad set the lowest framerate you get like 30 fps. The idea is for fluidness not jerkyness. Anything like aircraft shadows or lens flare. Just hogs framerates and doesnt really take away from your flight sim experience at all. put your screen at 1280 by 1024 and run fs in 1024 by 768 this will give your eyes the appearence of running it in 1280 mode. or if your monitor can only handle 1024 by 768 then run it in 800 by 600.
Always turn your firewall or antivirus off. This hogs framrates. (use this tip at your own risk)
Make sure you dont use the xp format look. right mouse clik on the screen choose properties and click themes tab choose windows classic same with the start menu bar. Right mouse click the start menu click properties click classic start menu. Make sure you choose none as far as wall paper goes this will bring up a blue screen. Make sure you have no fancy turning or twisting mouse running. just choose the basic mouse pointer.
In bios make sure you FSB speed is as high as it can go. For me thats about 200 fsb. It might be higher on yours. IF the fsb speed is to high your computer wont start up and will revert back to your bios so you can reset the fsb speed that might work. upping the fsb speed will majorly increase framerates. You might try a high performace profile if you have that avaliable on your computer in bios config. This will push your system to the max without compromising it.
I dont recommend overclocking your graphics card if you choose to do so. Only do it just a little bit.
Turn off all things in the bios you dont need like on board modem or pci modem onboard whatever if dont need it.
Also turn spool off in the process tab in the task manager. This stupid things takes up more memory then anything.
Mipmap detail in fs shouldnt be any more then 4 or 5.
Global texture size shouldnt be set more then high if you want massive this will give you just better looking aircraft detail any maybe a few other minor things.
If you dont mind flying alone turn traffic to 0% in fs. This will give a big increase in framerates.
Also make sure not one thing is in the task tray.
When fs 2004 loads hit alt tab then hit ctrl alt delete which will bring up task manger go to the processes tab find fs2004 and right mouse click it and set the priority to high or realtime this will give fs2004 a big jump.
Let me know how it goes :)
Hopefully doing all of this will gain you some major jumps in framerates.