I think this is more of a texture loading issue on my machine (but I could be wrong).
Yes, it is a texture loading problem, but the fact you hear sound pops and cracks when this happens, means it's related to a problem which can be either due to IRQ sharing, OR PCI latency.
I can see when textures loads and the objects are just pain gray for a while, even on FS9, but I don't have any audio problems even when it's actually loading and the hard drive light is on.
So, if you hear the audio cracks, visual stuttering it's the minimum you can expect.
Fact that is happening at JFK, it's only because it IS a big scenery, with many textures, and it resides in a place were lots of textures are loaded apart for the scenery, as usual, it's not "just" the scenery, it's the whole. If your system was just on the borderline of being able to load everything without audio/video stuttering AT JFK without "our" JFK, adding it might simply crossed a limit, were your system can't cope with the load anymore. Note that this doesn't have anything to do with frame rate. If anything, it might be even worse, the higher the fps is. Fact that FS9 doesn't use Dual Core to do texture loading, doesn't help either, but the more significant issue, in your case, is the audio stuttering, which indicates something is not performing as it should.
A thing to check might be under the Peripherals screen in Windows, to check which IRQs has been assigned, and if the audio card is sharing its IRQ with something else, especially with disk controllers. Sometimes it's possible to fix the problem by moving the audio card to a different slot, the mainboard manuals usuall have a page which explains how IRQs are shared between PCI slots and the internal peripherals.
