rds sql server with db.t3.small is slow

Question

I have this query using EntityFramework Core:

                if (_context.Users.Where(u => u.EmailAddress == user.EmailAddress).Count() > 0)
                       ...

After not accessing the db for a few minutes, it takes more than 14 seconds.

Right after this, I save a new row to the table, this takes 1.5 seconds.

Does it make sense when using db.t3.small?

The table has about 10 rows.