Hi Adam,
I had identical issue with 3 HTTP requests. Here's what solved that:
1. Use Windows Auth (not basic auth) explicitly: configure web app
with authentication mode="Windows" and allowed roles.
2. Disable anonymous access in IIS.
3. Use explicit Windows credentials to connect to server (otherwise
connection can switch to built-in Guest Windows account, you can check
this in IIS log).
4. Turn on UnsafeAuthenticatedConnectionSharing to avoit multiple HTTP
request per each request to Raven.
In my case use of Windows auth instead of basic decreased number of
calls from 3 to 2. Connection sharing made auth happen only once per
session.
Keep in mind, that:
1. You will still have 2 HTTP calls before *first* save operation -
this is the way HTTP auth works. Sunsequent calls will use same
credentials by default.
2. Connection sharing is safe only if you're using single user account
to access Raven from this machine. Because all subsequent requests
will use same credentials as first one.