I have the same FPS issue with EGPE and have tried the suggestions listed above but no success.
Am running P3D V3.3 and using ORBX Scotland. Have UK2000 airports installed and even Oban. All of them run perfectly. My FPS are crippled at 25 and this is what I get above Edinburgh downtown. When in EGPE and surroundings (e.g. 15 miles) I get in average 15 FPS but with huge variations, meaning that in some EGPE spots I get above 20.
Have tried everything , uninstalling and re-installing, playing with the sim720 settings etc
Disabling ORBX Scotland did not make a difference.
But when ORBX Scotland is enabled and Sim720 EGPE is disabled, I get my 25 FPS again in ORBX EGPE 'default' .
Not quite sure what the conclusion with Gsumner was, but even playing with the ORBX 'hybrid' vs regions mode is not an option nowadays with FTX Central 3 as this logic appears to have been sunset in between.
Again, this issue is absolutely unique to EGPE which is unflyable as it stands.
But am delighted with Oban and looking forward to add Caernafon and Stornoway as soon as my EGPE miseries are sorted out.
Your recommendations will be appreciated !