Use the easy Task Factory Upsert Destination which has been written specifically for performance and to speed up your development time. The component can be configured in seconds, and it can handle many more scenarios like looking for row differences or logging the number of inserts and updates to a variable.
Speed up your SSIS package run by up to 700x! Because there are no row-by-row operations to update data, Upsert Destination will take a load that might have taken an hour down to under a minute in many cases. Task Factory components use SSIS for what it's good for and SQL for what it's good at by using merge code behind the scenes and updating tens of thousands of rows in the time SSIS would have updated a single row.