The present invention provides an HDD performance enhancement system that utilizes excess disk capacity as cache memory to enhance the I/O performance of the drive. The cache memory is distributed throughout the disk, for example in alternating tracks, sectors dedicated to serving as cache, or other distributed cache track segments or segment groups. Distributing the cache throughout the disk reduces the physical distance of the I/O head to the closest available cache location. The system minimizes the write seek time by storing write data in the closest available cache location. High utilization data blocks are stored in multiple cache location locations to reduce read seek time for high utilization data. The cached data is eventually written to permanent memory and cleared from the cache during idle or low data storage utilization periods.