14-18 FPS? You're not looking at a drop from 30-40 FPS then.drop to around 10 from a range of 14-18 before that point in the 744.
My best guess is that your system simply can't handle it.
FPS drop to around 35 FPS for me with the 744, but go up to 100+ FPS once I'm on the climb-out.
It's all relative. My suggestion is drop the detail.
I'm personally finding it to be very good! I've got heavier scenery than this installed.
@Martin: the 1.1 patch without the Landclass (I removed it) is fine - it seems that at the time I downloaded it, there was still an issue. I agree with previous comments that the approach lighting needs tweaking to make it more discernible.
GREAT WORK!

Best regards,
Robin.