Bart Czernicki has a detailed post showing how Silverlight 2.0’s multithreading can improve performance. He took my counting primes code and  adapted it for parallel processing. On my quad core system the results are impressive:

As you can see by squinting at the screen grab, the processing time went from 0.43 to 0.20 seconds.

Multithreading is getting a bad rap in some quarters, because it greatly complicated debugging. On the other hand, if you have an app which does some heavy duty calculations then performance benefits like this are worth a little pain.