Hi Vinoth,
Any data required by the database to be shown / displayed is loaded to the memory. Hence when you select values from the column to select in the filter, the column data is loaded to the memory during the design time.
You can check which all columns are loaded from M_CS_COLUMNS view with the table_name = <your table name>.
Also M_CS_TABLES which help you understand if the table is already loaded fully or partially to the memory.
Regards,
Ravi