Improving application performance in Couchbase can be achieved by creating indexes for common queries, although the process can be challenging when using Spring Data due to the lack of clarity in generated queries. This issue can be addressed by setting the DEBUG log level for the AbstractN1qlBasedQuery class, which allows N1QL queries to be printed in the log, similar to Hibernate's show_sql attribute. Users can configure this by modifying the application.yml or logback.xml files, with the latter requiring the addition of the logback-classic dependency. Once configured, the application will output detailed N1QL query logs, aiding in the creation of effective indexes. Some users have reported difficulties with logging in certain Spring Boot and Spring Data Couchbase versions, suggesting the use of specific packages from Spring Data 4 onwards to resolve such issues.