Put the options (the only slider available) at minimum and start from that.
If even at minimum you cannot run X-Plane 11, then your machine is not powerful enough.
XP11 has almost no controls on graphical options so you should have a pretty powerful machine tu run it.
One of the worst choices of programmers was to enable at all options level the extended dsf feature, that kills the fps even on powerful machines, and generates really huge stutters, expecially if you use some photo scenery overlay. You can disable this option only inserting some text lines in the internal X-Plane settings file, and doing this each time X-Plane updates itself.
Easy and "user firendly" doh?!?!