There are a few things to consider when dealing with a lower than average framerate. I will list them here and hopefully you will be able to increase your overall performance.
1. Try to run the game on low settings\low quality renderer. If the game is still facing performance issues, then try updating your video card drivers, and DirectX.
2. If these issues persist try running the game without anti aliasing, vertical sync, shadows and ground clutter.
3. If you are on an ATI video card make sure ‘Anti-Aliasing’ and ‘Anisotropic Filtering’ are set to ‘Application Controlled’ in the Catalyst Control Center. Disabling “Morpological Filtering” in the Catalyst Control Center will usually result in improved framerates. Disabling “ATI Overdrive” may result in increased framerates in some configurations.
4. If you are on an NVidia graphics card then make sure “Power Management Mode” is set to “Prefer Maximum Performance” in the NVidia control panel. Ensure “Anti-Aliasing” and “Anisotropic Filtering” are set to”Application Controlled” in the NVidia Control Panel and “Transparency Anti-Aliasing” and “Ambient Occlusion” are set to”Off” in the NVidia Control Panel.
5. If none of these steps helped try performing a clean boot to ensure no background programs are causing the system to much strain, resulting in low game performance.
*Please Note* If you have any biometric software (Fingerprint readers) on your system take care not to disable it.
You can run this utility by following the steps below:
1. Press the Windows + R keys simultaneously.
2. In the Run window that appears, type "msconfig" without the quotes and click OK.
3. In the System Configuration window, click on the Startup tab.
4. Click the Disable all button.
5. Click on the Services tab.
6. Click on the checkbox next to "Hide all Microsoft services", which will remove all of the Microsoft services from the Services list.
7. Click on the Disable all button.
8. Click OK.
You will then be prompted to restart the computer, which you need to do before proceeding.
If the game is still having performance issues you may also try disabling Flash and any program that may use flash as it may be using up enough system memory to cause a lower framerate.
These are just general steps to take when you are experiencing lower than average FPS.
Here are some more advanced things to try as well,
Go to your RIFT folder wherever you installed the game and find the rift.cfg file. Open this with a notepad and navigate to the “MainThreadCPU =”
Change the value after the “=” sign to “0″ which will allow RIFT the option to choose between the best available core (it switches between those available instead of being contained to one). If you altered the value properly than the final product should resemble the following:
“MainThreadCPU = 0”
Next we are going to be doing some more tweaking to the rift.cfg file,
Open the “Rift.cfg” file in the root directory of your Rift install and find the following line:
“VFXLimit = 750”
Change the default value to 10 and add the next line above it with the corresponding value:
“VfxCullDistance = 256”
The final product should resemble the following:
“VfxCullDistance = 256”
“VFXLimit = 10”
After editing the values above find the “LightingComplexity” value and change it to the following:
“LightingComplexity = 10.000000”
Next change "AmbientOcclusion=True" to False.
At this point you can try running the game again, once the game has started up bring up your task manager using Ctrl+Alt+Delete and go into the processes tab. Right click on the Rift process and set the priority to High.