If the lookup table is on the same database as the source table in your mapping and caching is not feasible, join the tables in the source database rather than using a Lookup transformation.
If you use a Lookup transformation, perform the following tasks to increase performance:
Use the optimal database driver.
Cache lookup tables.
Optimize the lookup condition.
Filter lookup rows.
Index the lookup table.
Optimize multiple lookups.
Create a pipeline Lookup transformation and configure partitions in the pipeline that builds the lookup source.