A garbage collector keeps a log of recent system usage. From that usage thus recorded, it determines whether a time slice whose duration a maximum-mutator-utilization ("MMU") specification prescribes and whose end time is the same as a prospective future collection pause will contain more than the maximum imposed by the MMU specification on the time slice's garbage collector time. The collector uses that determination to arrive at a compliant length for a pause that is to start at a predetermined time or to find a time at which a pause of a predetermined length can start without violating the MMU specification.