A distributed storage network method begins by determining an encoded data slice to rebuild, determining a storage set of distributed storage units associated with the encoded data slice to rebuild, determining an historical performance level of each distributed storage unit of the storage set of distributed storage units, determining an estimated performance level of each distributed storage unit of the storage set of distributed storage units, selecting at least a decode threshold number of distributed storage units of the storage set of distributed storage units to produce selected distributed storage units, determining an encoded data slice partial aggregation scheme for the selected distributed storage units, sending encoded data slice partial request messages to the selected distributed storage units, and receiving encoded data slice partial response messages and extracting encoded data slice partials from the encoded data slice partial response messages to rebuild or verify the encoded data slice.