First, I am not a Windows expert, and I do not take credit for these tweaks. I have accumulated them from a few websites and I am consolidating them here and putting my additional thoughts to them for clarity. Please use these tips at your own risk, and if you are just not sure about changes you are making, do not do them.
Always make a system restore point before making any major changes to your system settings. To do this:
1) Open the Control Panel (all items view, not the consolidated categories view)
2) Open the System control panel by clicking on the "System" icon
3) In the left pane, click on "System protection"
4) On the window that comes up, the very last option is to create a system restore point. If you need to use this later after something goes haywire, just open the start menu and type "system restore" press enter, and run the wizard that comes up choosing this system restore point you have made along the way.
I. Disable Windows Aero Theme.
Windows Aero is a resource and video card hog. It takes a surprising amount of system resources to run this feature. Even when you are not looking at its effect while your game is running in full screen, all the resources needed to run this feature remain tied up by the system.
1) Right click anywhere in the open space of your desktop and choose "Personalize"
2) At the bottom of the window that comes up, choose Windows Classic. Yes, this looks like you are running Windows 95, but it will make a remarkable difference in your video processing speed. You can safely make some personalization to the classic theme such as colors of the window panes, etc.
II. Disable additional Windows graphics and visual effects.
1) Open the start menu and right click on "Computer" (middle right of the start menu)
2) Choose "Properties"
3) On the left, click "Advanced System Properties"
4) On the "Advanced" tab, under "Performance", click the "Settings" button
5) Click on the "Adjust for best performance" radio button, you will notice that all of the check boxes below become unchecked. This is because all of these animated and fading graphics effects when you click or mouse over something all cost you performance. You can turn back on "Smooth edges of screen fonts" and "Use drop shadows for icon labels on the desktop" as they are passive settings that do not tap into the video card every time you mouse or click. Turning these options off will make Windows less dazzling, but will free up video resources to play the game with. While you are playing the game and not using these Windows effects, they are still taking up video resources so they are again available when you exit the game.
You can stop right here and you should notice some improvement in your overall Windows speed and video performance in the game. You may not be able to go straight to all high settings, but it should be noticeable. If not, or if you do not like these changes, you can undo these (all or in part) in the same way you set them or simply run the system restore wizard as I said above to completely revert back. If you want to free up some more resources, continue with the following steps. If you are fine with these settings so far, make another system restore point and proceed.
III. Disable Search Indexing
How often do you do a "search" or do "find" for files on your computer? If the answer is not that often, then you can safely turn off Search Indexing. This is a Windows feature that uses some of your available memory to store an index of files on your computer to speed up a search for files. Whether you are searching or not, this information is held in reserve, tying up memory. The ramification of turning this off is that a search for files on your computer, when you actually do one, will take longer.
1) Open the start menu and right click on "Computer" (middle right of the start menu)
2) Choose "Manage"
3) On the left under the frame for "Computer Management", click the + to expand "Service and applications"
4) Click on "Services"
5) On the new pane that opens, scroll down to "Windows Search"
6) Right click on "Windows Search" and choose "Properties"
7) In the window that pops up, where it says "Startup" click the drop down menu and choose disabled. 8) Click "Apply", then "Ok" and close out the windows you opened in this process.
This service will no longer load when Windows starts. This will speed up your system start time as a search index will not be created and will improve performance as memory is no longer tied up storing this information.
IV. Disabling Windows Services that you do not need or use.
Have you ever opened your task manager with ctrl-alt-del and looked at all of the processes running and wondered what all of them are? Whether you have or not, by default there are many processes running in Windows that you probably do not need or rarely use that are tying up memory and CPU processing power. Whether you are making use of the service provided by these processes, they are being managed by the CPU and utilizing memory that could be available to your game.
When going through these, if there is something you think you use, simply do not disable it. However, the more you disable or change to manual start, the more processing power and memory you free up to play the game with. This is a very similar process to disabling Windows Search as we did above.
1) Open the start menu and right click on "Computer" (middle right of the start menu)
2) Choose "Manage"
3) On the left under the frame for "Computer Management", click the + to expand "Service and applications"
4) Click on "Services"
6) Right click on the services below that you wish to disable and choose "Properties"
7) In the window that pops up, click the drop down menu and choose "disabled". You can choose "manual" and the service will only be started when and if you actually need it, but then it will remain running whether you continue to need it until the next time you reboot.
8) Click "Apply", then "Ok" for each one.
Application Experience (If most of your programs are up-to-date and you aren’t experiencing issues with applications crashing, you can disable this service without concern. This is a database of third-party programs that windows has a hard time running (not common) and needs to alter its behavior to accommodate).
Desktop Window Manager Session Manager (100% disable of all Aero effects options)
Distributed Link Tracking Client (A service for creating links to files on network computers so that you can open files on other computers from shortcuts on your own. Safe to disable if you do not do this).
IP Helper (Provides tunnel connectivity using IPv6 transition technologies. If this service is stopped, the computer will not have the enhanced connectivity benefits that these technologies offer. However, very few ISP’s offer a native IPv6 network to home users and no reason exists to have both IPv6 and the tried and true IPv4 on a home network, and if none of this even makes sense to you, you can disable this).
Offline Files (If you do not regularly store entire websites for offline viewing, you can safely disable this or set to manual if you occasionally do)
Portable Device Enumerator Service (Enables Windows Media Player and Image Import Wizard to transfer and synchronize content using removable mass-storage devices. If you do not do this, safe to disable or set to manual).
Print Spooler (If you do not use a printer it is safe to disable, set to manual if you occasionally print)
Remote Registry (This is one of those not needed services unless your computer is managed by a system administrator over a network. One of the first that should be disabled on a home network. If you are paranoid about security, disable this service. Even if you are not or do not care, disable it anyway. )
Secondary Logon (Enables starting processes under alternate credentials, i.e. running an application as another user account on your computer. If you do not know how to do this or have never heard of or think you do it, you can disable or set to manual safely).
Security Center (This is the pop up that you get in your system tray constantly if you have your firewall, anti-virus or Windows Update disabled. If you manage your computer security conscientiously you can disable this as it is only eating resources to monitor your good practices. If you need those reminders in case you have turned something off, then leave this on. This is only the notification pop up and not any of the actual services)
Server (Supports file and print sharing over the network for this computer. If you do not share files/printer over your home network, this is completely safe to disable).
Tablet PC Input Service (If you computer is not a tablet, you do not need this service running).
Themes (Completely locks out all themes except Windows Classic as options under personalization.)
Windows Error Reporting Service (Disables the pop up to tell Microsoft why your Windows crashed if and when it does. If you do not care about this memory eater, turn it off.)
Windows Media Center Service Launcher (Don't use Windows Media Center, disable it, or set to manual if you occasionally do).
You will need to reboot your computer for these changes to take effect. If after making these changes, you do not like the results or encounter problems, run the system restore wizard and choose the restore point you made before making these changes.