Hi I didn't realise the post was last year until I read it after I posted. My problem was that I loaded FS2 last year & found the frame rate to be so bad as to be unusable, so I deleted it. Then recently I gave it another go on a spare SSD & all is well. Also I have upgraded to Win 10.
I should also have posted a big thank you to chrispriv & all the others who produced the BC scenery. it is a pleasure flying in that area in FS2 as I fly there a lot in FSX. What a difference! ChrisD