Responsiveness/performance IIS web site

I am using a HttpModule in a IIS web site and fire 14,000 POST requests in 8 sec. that are inserted (logged) in a Sql server database (table without index).

However only 1,200 requests are logged, apparantly all others are somehow missed and I dont't know why.

When I add Thread.Sleep(10) after UploadStringAsync(..) I miss only approx. 50-70 messages out of 14,000. Is it an IIS issue (5.1 on this machine), or is the idea of 14,000 / 8 sec. absurd?

Edit @DForck42:

No select statement is in use anywhere; the insert statement (stored proc) is:

Entlib.Cmd.Parameters["@datetime"].Value = timestamp;
Entlib.Cmd.Parameters["@url"].Value = url;
Entlib.Cmd.Parameters["@body"].Value = postdata;

using (DbConnection connection = Entlib.Db.CreateConnection())
            {
                Entlib.Cmd.Connection = connection;
                connection.Open();
                Entlib.Cmd.ExecuteNonQuery();
                connec开发者_如何学JAVAtion.Close();
            }

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This could be a connection limit problem. There is a limit on how many simultaneous connections IIS will handle (5.1 on XP Pro will only handle 10, for instance). When the connection queue limit is reached, IIS will start to reject requests. Check your HTTPERR log for rejected requests.