From what I have read over the Internet OR is quite demanding in terms of GPU requirements and stable frame rate.
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Here are the requirements for OR (
https://support.oculusvr.com/hc/en-us/articles/201835987-Oculus-Rift-Development-Kit-2-FAQ):
Q: What are the minimum requirements and recommended specifications for the Oculus Rift Development Kit 2?
A: Minimum requirements: A computer running a Windows 7 or higher, Mac OS 10.8 or higher, or Ubuntu 12.04 LTS operating system, 2 USB ports (at least one powered), and a DVI-D or HDMI graphics output.
Recommended specifications: A desktop computer running a dedicated graphics card with DVI-D or HDMI graphics output, with capability of running current generation 3D games at 1080p resolution at 75fps or higher.
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As you can see you GPU should provide 75+fps.
Take into account that ED is not optimized yet, and the frame rate might be improved. It is a known issue that ringed planets have significant impact on the performance.