Kryptos wrote:
it is a beta

What's a beta? Silverlight 1.0 is RTM.

Silverlight 1.1/aka 2.0 is an "alpha" and has no "Go live" license available yet so shouldn't be in use on any 'production' site.

The Microsoft Downloads site is Silverlight 1.0 I believe, and given performance of other Silverlight sites I suspect any performance problems are nothing to do with Silverlight (but I'm too lazy to analyse the page and http traffic to work out what IS causing the problem).