Sahred lookup and persistent look ups are the lookups which are cached once and are used by more than one ETLs. This is useful when the data in the table which is used for the lookup is huge and if this table is used in more than once, then in every ETL considerable amount of time is used for casching the table everytime if lookup is used individually.Persistence lookup hence helps in performance improvement. shared cache: Data in the cache can be shared between multiple transformations. It is just sharing the lookup cache. Persistence cache: The cache can be reused across multiple session runs.