Load times are related to the number of samples that must be preloaded. The Bosendorfer has a huge number of samples with its four dynamic layers, etc.
However, there is also the possibility of a disk controller compatibility issue with Giga. One of my MOBOs has a Promise ATA100 controller that slowed load times to a crawl - loading a sample set that should have taken 1 minute was taking about about 20 minutes. I could find no resolution so I moved the disks to the regular IDE channels and then everything was fine!