Which SQL Server feature is utilized to improve DTS performance?

Incremental loading strategies are focused on improving data transfer efficiency by only moving the data that has changed since the last load. This approach minimizes the volume of data processed during each extraction and load cycle, which can significantly enhance performance. By selecting only new or modified records, incremental loading reduces the time and resources required to execute data transfer operations, leading to faster completion of DTS (Data Transformation Services) packages.

The other options, although useful in different contexts, do not directly address the performance optimization of DTS in the way that incremental loading strategies do. For instance, database mirroring is primarily a high availability technique rather than a performance enhancement method for data transfers. Replication services are used for distributing data across different servers but may not streamline the data load process as efficiently as incremental updates. Clustered indexes optimize query performance but do not specifically enhance the DTS data movement process in the same manner that incremental strategies do.