I have over 25 hours on X plane 11 v.3 with great success and good enough frames per second usually around 25-29 fps. I updated X plane 11 to v.5 and my frame rate went down to less than 5 fps after 2 minutes with the same settings used before on version 3. One blogger reported improvement by limiting the number of AI aircraft. I made this change and eliminated all of the AI aircraft and my frame rate bumped up to 17-19 fps for approximately the first 5 minutes and then slowly dropped to less than 5fps again after 12 minutes of flying. My X plane 10 runs 35-40 fps on the same computer. I am looking for a link to be able to install v.3 again until a fix for v.5 is found. I have been involved with another beta program that enabled me to choose an earlier version of the beta when a later version was incompatible.