GCM Android push Notification 5 million messages in dry run mode

[Mushtaque]

My APP server process sent 5 million messages to GCM using HTTP post with dry run parameter,https://android.googleapis.com/gcm/send?dry_run=true

It took 3 hours. I tried using single connections as well as concurrent 10 connections, the result is the same in both cases. Each multicast message has 1000 fake registration IDs.

The requirement is to send 5 million messages within 30 minutes. Is there any another way to achieve the same.

Thanks 

Mushtaque