The below code will save you a round-trip for each of your Vault API web service calls.
|System.Net.ServicePointManager.Expect100Continue = false;|
If you have your own Vault client, you should put the code sometime during startup. If you are running inside an Vault client from Autodesk, this value should already be set to false.
I don’t have much more to say on this. You find out more about the Expect100Continue property on MSDN.