This site is being deprecated.
Please see the official X‑Plane Support page for help.
I think your options are probably to decrease the rendering settings, decrease the number of monitors you use, or upgrade the graphics card. It sounds like your set up is too demanding. If you use a lot of add ons you could try removing them as well as they can be a drain on system resources.
Here is a tutorial on setting the rendering options for your machine.
This site is no longer being actively maintained.