This depend on what you are trying to do with the airtable Data. Most of the time you will use a RG with Get Data from API
But in some case you may want to display only one item. You will also use GET Data from API but with :filtered options and :first item
Bigger your airtable DB will be, slower it will be too. Bubble will need to load all data (but you can use filter I think to laod them all). But it’s not so different than from Bubble database calling. There’s a lot you can do to speed the loading of data to get thing load faster. Also, the application is not directly slowing down by the DB size. This depend on how many data you are calling! This will not be different with Airtable. One difference with Bubble is when you use field that reference other DB. In some case, this can increase the data loaded a lot. But again, there’s a lot of thing you can do to make your app faster just by managing correctly the call your are doing to DB and the structure of your DB.
You are probably saving a list of thing in a field that is not a list. You don’t need to store data into Bubble DB if you are calling Airtable DB. You can just display data. You can use regex to split text and create an array too if needed.