Redirect result will return the HTTP redirect result (302) to the browser, with the whole parameters in the url. If you're passing model properties in the routevalues, they will be serialised to strings.
So, as you said the browser (at client side) will see all those parameters, and the browser will issue another GET request to the new url.
The recommended approach in this case it to use TempData at the controller to set all your server-side data. Then redirect to the new action.
TempData["mymodel"] = myModel;
return Redirect(Url.Action("newaction", "newcontroller"));
And in the new Action, you can just retrieve your model from TempData