In this summary, ClickHouse enables users to improve query performance by utilizing dictionaries in data modeling and optimization. The `stations` table is normalized with a separate table for country codes, states, and locations. A dictionary called `stations_dict` is created using the `stations` table as its source. This dictionary can be used to accelerate queries that require location-based lookups. By leveraging the primary key of the `country_code` column in the `stations_dict`, users can optimize their queries for faster execution times. The example demonstrates how to use dictionaries to improve query performance, especially when dealing with complex data models and large datasets.