fast convergence a multi-DMVPN clouds with multi-hub networks

hello all

i have 2 main sites (HUB)

and a bout 40 branches(Spokes) they are connected with multiple DMVPN clouds (3)

but when in a branch one link goes down i have to wait for NHRP to go down to switch to my second link it takes about 50 seconds to switch witch is a lot how can i fix this issue?