I think it was the eDRAM that made difference, allowing lots of transparent redraw to be handled: "Embedded DRAM gives 48 GByte/sec memory bandwidth to eliminate pixel fill bottleneck." - http://research.scee.net/files/presentations/agdc2000/ThePow...

Granted that was years ago, so I might be mistaken. But it's still a lot of speed for a device that was made more than 13 years ago...