Spring Boot Batch Inserts Cut API Response Time 40% by Fixing Transactional Misuse

A common misuse of Spring Boot's @Transactional annotation causes Hibernate to execute a separate database query for every item saved inside a loop, leading to severe performance degradation. For example, saving 50 items this way triggers 51 SQL queries instead of just 2. The fix involves enabling JDBC batch processing via Hibernate properties in application.properties and replacing individual repository.save() calls inside loops with repository.saveAll(). This change allows Hibernate to group all inserts into a single batched statement, drastically reducing database load. The optimization reportedly reduced API response time by 40%, highlighting that @Transactional manages transactions but does not automatically batch queries.