Slower Framerates with the Freighter

Just noticed this tonight, but I appear to be getting on average 7 - 10 FPS less with the freighter variants than I do with the passenger models.

Reloaded FSX a number of times with various scenarios, and there definitely appears to a consistent framerate drop.

Anyone else notice this, or am I just goin' a bit mad, Ted ?

2 x E5450 Xeon Quad Core / 16gb ECC, GTX 285

Example: Freighter EGLL Active RW approx 23 fps / Passenger approx 30-31fps