BGP-ORR Scaling on vRR

[Dhamija Amit]

  Hi
I am testing  the feature BGP-ORR to have a centralized Route Reflectors in our network.
The feature works well and it ensures optimal routing to the nearest clients.
I have some concerns on the scaling of this feature, with around 150 ORR Clients/Groups in one RR and with scale of Internet Prefixes 

around 650K Prefixes with 10M Paths it takes around hours to converge the prefixes to the rest of the client routers.
I understand vRR should perform best path computation per update-group and each ORR client is one update group, so with around 150 update groups each prefix needs to be updated per group.
Can some one give insights on how many ORR clients do we need to configure in one vRR to have optimal convergence in network.

RegardsAmit Dhamija