A method for execution by a dispersed storage and task (DST) execution unit includes generating a first compaction object by performing a compaction function on a first previously compacted object and first data slices that compare favorably to a cold access threshold. Storage of the first previously compacted object in a cold memory region is replaced with the first compacted object, and the first data slices are removed from prior storage in different memory regions. A second compacted object is generated by performing the compaction function on a second previously compacted object and second data slices that compare favorably to a hot access threshold. Storage of the second previously compacted object in a hot memory region is replaced with the second compacted object, and the second data slices are removed from prior storage in different memory regions.