The confusion here stems from the fact that this request was sent on a reused connection. The client finished sending the request to Fiddler at 11:31:56.355 and Fiddler finished returning the response at 11:31:57.497. Most of that time was the 1.076 seconds spent in figuring out what Server IP or Proxy IP to use; after that determination was made, a connection to reuse was pulled from the pool.
Spending over a second in Gateway determination is unusual and suggests something odd is going on in the client's non-Fiddler proxy configuration (e.g. a very slow PAC script).