Well for one there are several things to consider about the performance that many of us are getting with these Dream wallpapers.

For one, the video drivers for Vista are still quite premature. This could be said for nearly any video card manufacturer, although current drivers work better with some cards than with others. To sum it up, however, better video drivers should definitely mean some sort in increase in performance when it comes to DreamScene in general.

A second point that is worth noting is that DreamScene is still in a "preview" phase. This product is not completely finished, and many of us here feel that performance should increase once the final version has been released. Afterall, the entire point of DreamScene was to put a majority of the workload on the GPU, instead of the CPU.

What it all boils down to is patience, really. This is a brand new product on a brand new Operating System running on brand new video drivers. Give it some time for all of the components to flesh out it's problems and DreamScene will evolve into a truly beautiful experience for all of us here.

Here is a post that sheds a little light on that.

https://forums.wincustomize.com/?forumid=153&aid=144461