Best (free) database/spreadsheet provider for sync time

Hello AppSheet :slight_smile:

My end-users are complaining that my app syncs too often and too slowly. I changed the architectural aspects of the app to improve sync time but this isn’t enough for end-users who are always on the go. Right now I use Google Sheets and the help documentation suggests using a database provider instead. Which free database provider is fastest? Would Excel be better than Google Sheets?

Thank you.
Tiffany