I now suspect that this problem is somehow related to ATI HyperMemory. It mainly seems to affect the newer PCI-E, X1xxx and HD series cards.

I ran some tests yesterday by rebooting with restricted system memory. I restricted the system RAM from it's 2GB through 512MB and 256MB right down to 128MB and the loading bar delay was reduced to about 20 seconds from the usual 2 minutes, but the game was obviously unplayably slow due to lack of RAM and severe swapping to disk. I also tested running on a single CPU core and that didn't make any difference.

This could be seen as evidence of "the more system RAM you have, the worse it gets", but I think it goes further than this. Personally I have a hunch that it's the hypermemory area allocated by the ATI driver that is somehow causing the slow loading problem with MTW (which is probably quite simply incompatible with it for whatever reason). The less system RAM you have, the less hypermemory can be allocated. In theory hypermemory should cause a problem as it's not a fixed reserve, but more a of a dynamic maximum available.

Unfortunately it doesn't look like it can be disabled or adjusted in any way - hence the problem.

I had a similar problem some years back with an Nvidia card (a 7300GT), though that was an AGP card (running in my old motherboard). I seem to remember that reducing the AGP aperture down to the minimum reduced the loading delay significantly, but I don't think it eliminated it. So it seems probable that MTW has issues with AGP Texture Acceleration/HyperMemory on certain newer graphics cards, but not with Nvidia's TurboCache?

Interestingly MTW has the AGP slider in the video options, I've never seen this make much difference, but it's absent from Shogun and that does not have this issue at all. I would guess that something CA added to the game, regarding this AGP slider, is tripping this fault.