Continual NTLM Authentication

Hi. This is not actually a Wireshark question per se, so, if I'm out of line for asking it here, please let me know. I will take it like a man :-)

I am using Wireshark to analyze/improve the performance of a .NET 2.0 application. It is a WinForms app, which calls an ASMX Web Service.

What I have found is that, for each and every HTTP POST, to MyWebService.asmx, an NTLM Authentication sequence is executed, as follows:
1) Client sends POST, 2) Server responds with '401 Unauthorized', 3) Client sends POST again, but this time with the necessary 'Authorization:' Header, 4) Server responds with '200 OK'.

This sequence is executed even when the client hits a button that causes 4 consecutive POSTs. Each of these POSTs, from the same client to the same server, causes a NTLM Authentication sequence. This adds an extra round trip for each request, which has a significant impact on performance, since the client and server are separated by a high latency path.

My "guess" is that one of the following might cure this:

A) Include the Authorization header in the initial POST, so the server doesn't have to demand it via the 401.

B) Use a persistent connection, so at least only the first of the four POSTs will have to Authenticate.

Unfortunately, I am not a .NET programmer - I am a packetologist :-) - so I don't know what the developer needs to change.

Can anyone tell me if this is fixable with a not-too-complicated code or config change to the .NET app?

Thx much!

Feenyman99