A simple source filter on the source database can sometimes negatively impact performance because of the lack of indexes. You can use the conditional filter in the customized data object to improve performance.
Consider the following solution for conditional filter bottlenecks:
Use the conditional filter for multiple mappings that read from the same source simultaneously.
If multiple mappings read from the same source simultaneously, the conditional filter may improve performance.
However, some mappings may perform faster if you filter the source data on the source database. You can test the mapping with both the database filter and the conditional filter to determine which method improves performance.