A method is implemented by a network device in a network having a plurality of nodes. The method computes a remote loop free alternative (RLFA) next hop as a backup for a primary path next hop. The method improves RLFA computation efficiency for a Q-Space list of nodes in a Q-space for an endpoint node by reducing calculations of the loop free condition for a path from a source node to a destination node via a tunnel between the source node and the endpoint node. The method includes adding a neighbor node to a poison list where the candidate node is in the poison list and the neighbor node is not in the candidate list, the poison list indicating that a node is not a candidate for Q-Space, and determining the Q-Space list by removing nodes from poison list from the plurality of nodes.