I made an app and started solely with Airtable. My airtable base has around 1000+ records, and I use filters to display only specific contents on some pages.
In my experience, you won’t face slowdown if you use Airtable. However, with external bases, lists sometimes do not filter all the data correctly (and hence show all the records instead of only the filtered records).
I used the app for only about 2 months before I discontinued due to complaints from my customers about the app itself being slow, but that was not because of the Airtable base, it was because I’m located in South East Asia. I’ve been waiting months for Adalo’s performance improvements to solve this and get back into the game