Is there a rule of thumb to follow in regards to FPS?
I reported in another thread that I was averaging upper 30's to mid 40's in FPS but my target was set at 45, I have discovered that I can easily double that by adjusting my frame rate target to 90. Now I am averaging upper 70's and low 80's with an occasional jump into the low 90's when using cockpit view with default scenery and such.
  From spot view it drops into the upper 40's and low 50's, add-on's like ready for pushback and certain other add-on's bring it down a bit more. The Hangzhou airport scenery really brought it down.
  So I guess my question is, what is the purpose of the frame rate target and should it be set as high as possible? or should it be set a bit lower than the actual FPS that the graphics are  maxing out at?

  You were right on everything except it's p-4 2.66 gHz.
I see your point, so I will set my target lower, and really I was just experimenting to see what I could hit, it flicked into the 90's a time or two, and this is with all the detail maxed out.
Thanks for the insight.