Announcing improved networking performance for Amazon EC2 instances

Amazon EC2 instances now provide a maximum bandwidth of 25 Gbps. This feature is available on the largest instance sizes of the M4, X1, P2, R4, I3, F1, and G3 instance types. Using Elastic Network Adapter (ENA) based Enhanced Networking, customers can utilize up to 25 Gbps of bandwidth. All of these instances, including those already running, can take advantage of the additional network bandwidth without any additional steps. 
Quelle: aws.amazon.com