But we also noticed that you cannot modify it. The Silverlight control actively keeps the IE process at "Above Normal" in the operating systems scheduler. You can reduce the process priority, but the Silverlight control will simply boost the host IE process up again. This has killed several laptops by exhausting the battery because the user could not stop the IE process in question.
IMHO, I feel that this is a very poor design decision. Enforcing their idea of what priority the process should run at is borderline virus like behavior.