px "graceful" ? gentler restart?

when reloading/restarting px, with hundreds of senders and dozens of receivers, each one reads the entire routing table into memory. the load on the system goes very high >100 for a minute or two. This can cause forwarding delays.

otoh, if the configurations are not initiallized, that also causes forwarding delays. anyways... ideal would be to have component restart in small batches over a few minutes to avoid the huge spike in load.

Start by tracing how reload and restart currently initialize the routing table for senders and receivers. Determine how restart batches could be staged, then verify that the load spike is reduced without introducing forwarding delays or using uninitialized configurations.

Written by the indexing model from the issue text.