A. Replace the Auto Scaling launch configuration to include c3.8xlarge instances; those instances can potentially yield a network throuthput of 10gbps.
B. Re-architect your ingest pattern, have the app authenticate against your identity provider, and use your identity provider as a broker fetching temporary AWS credentials from AWS Secure Token Service (GetFederationToken). Securely pass the credentials and S3 endpoint/prefix to your app. Implement client-side logic to directly upload the file to Amazon S3 using the given credentials and S3 prefix.
C. Re-architect your ingest pattern, and move your web application instances into a VPC public subnet. Attach a public IP address for each EC2 instance (using the Auto Scaling launch configuration settings). Use Amazon Route 53 Round Robin records set and HTTP health check to DNS load balance the app requests; this approach will significantly reduce the cost by bypassing Elastic Load Balancing.
D. Re-architect your ingest pattern, have the app authenticate against your identity provider, and use your identity provider as a broker fetching temporary AWS credentials from AWS Secure Token Service (GetFederationToken). Securely pass the credentials and S3 endpoint/prefix to your app. Implement client-side logic that used the S3 multipart upload API to directly upload the file to Amazon S3 using the given credentials and S3 prefix.