The server-side DGC implementation maintains a list (per client VMID) of
targets, each corresponding to a remote object for which the given client
holds a lease. The target list is implemented as a java.util.Vector which
scales linearly. If a given client hold leases to many objects
(e.g., 10,000+) in the same remote VM, the cost of adding a new target
to the list becomes very expensive.