A garbage collection process, wherein a system, concurrently with execution of a mutator application that modifies a heap memory computes, for each of a plurality of regions in the heap memory, an estimate indicative of a time required to evacuate the respective region. Thereafter, during a garbage collection pause having a particular pause duration, the system selects a candidate subset of memory regions for evacuation. The system merges the estimates indicative of the time required to evacuate each region of the candidate subset and determines a remaining time during the pause. The system may determine that the total estimated evacuation time to evacuate the candidate subset of regions does not exceed the determined first remaining time, and may evacuate each region in the candidate subset of memory regions for evacuation.