Java Architect Handbook
Mar 22, 2026 · Backend Development
Hidden 70 ms Delay in Spring Boot: Tomcat Embed Bug Triggered by Swagger UI
After optimizing a Spring Boot channel service, a mysterious extra ~100 ms appeared per request; detailed tracing with Arthas revealed that embedded Tomcat repeatedly loads Swagger UI META‑INF resources, causing a 70 ms overhead, which can be eliminated by upgrading Tomcat or removing the Swagger dependencies.
ArthasEmbedded Tomcat BugPerformance debugging
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