Per packet or per destination would not be only relevant to VPN traffic, but for all traffic which uses CEF as a forwarding method.

Per destination is default in cef, and you can set it to per packet, but per packet would not be recommended as a thumb rule, as it can result into out of sequence packets.

Although you can choose to use per packet on a per case basis where, both the paths involved are of similar lateny or for traffic which is not delay sensitive.

HTH-Cheers,

Swaroop