Thanks FlightAce for a really good post. Unquestionably threading of scenery over other cores is clearly a last minute modification by ACES. Like ignoring SLI, multicore threading was never part of the original coding.
I have said it before - SLI and multi-core chips were well known at the time of writing FSX so I remain puzzled why they employed horse and cart approaches when they already new of improved programming opportunities based on upcoming hardware.
Further those of us who (stupidly) went to Vista and 8800 series video cards for the much advertised DX10 only got a preview which gave big performance hits in return for an almost indiscernable improvement in graphics. So we are still running DX9 on Vista - we could have stayed with XP (sounds of I told you so ringing the planet).
This may sound like an MS flame - its not, but it is disappointing that an inherently excellent upgrade of our favourite sim was let down by what I can only assume was haste to get it onto the market, and no doubt internal economies.
FS11 we are told is still 18months to two years away, so I have one more hardware upgrade to go, when the next generation of hardware arrives, then I suspect X will run really well.