Thanks to help from somewhere here I was able to track down my DMVPN connections problems to mtu size. I now have mtu set at 1400 and adjust-mss set at 1360.
I'm moving from IPSEC Site-to-Site vpns to DMVPN. Currently the fifteen IPSEC vpns are averaging 18ms ping times from hub to spoke while the DMVPN is averaging 50ms ping times. I have identical network connections in many of the offices and both DMVPN spokes are averaging 50ms while all of the IPSEC spokes are averaging 18ms.
How can I optimize the DMVPN GRE tunnels or is a doubled ping time typical when moving from IPSEC to GRE?