The profiles table previously lacked an index on the user_id column, causing slow query performance when joining with the users table. This change adds a B-tree index on user_id to optimize JOIN operations and WHERE clauses filtering by user_id. The migration file `20240614_add_user_id_index.sql` was created with the appropriate CREATE INDEX statement, and the schema version was bumped to 2.1.0 in the migration tracking table.
