Changes made in Stacker are updated immediately in the Airtable base. Whereas, changes made directly in the base update in Stacker ever 15 minutes.
We do have a fast sync feature available as a paid add on to all existing Stacker plans priced at $79/month. With fast sync, we are able to refresh all your data every 5 minutes, and sometimes up to every minute if not too much data is changing at once.
More on cache frequency here - Cache Frequency - Stacker