Systems and methods for reduced-overhead creation of persistent, point-in-time images (PPIs) are disclosed. The summary map is updated as needed when a block is newly freed or allocated after the latest PPI is taken. Therefore, PPI maps of previously created PPIs do not need to be scanned after PPI creation, thereby eliminating high latency disk reads and memory consumption for scanning. When a PPI is created, the active map and the latest PPI map are identical since the active map depicts the current allocation status of the blocks in the active file system. The active map only diverges from the PPI map when a block is allocated or freed in the active file system. Therefore, the active map can be used to update the status of blocks in the summary map when the status of a block diverges from its status as indicated in the latest PPI map.