Accessing cross domain iFrame contents

Recently we improved performance of one of our Ruby on Rails application. We used NewRelic tool to identify areas that were slow. One of which was file and image uploads to S3 from a text editor (Redactor). When a user uploads a big file or image - the app's server response time shoots up degrading the performance and overall throughput because the files and images were being uploaded via rails action. The server process was busy uploading file on S3 while other requests to server were being queued increasing the request processing time. To improve this, we decided to delegate