# Post metadata

**Title**

Why Your Spring Boot App Takes 8 Seconds to Start: A Bean-by-Bean Diagnosis

**Slug**

`spring-boot-startup-time-bean-by-bean-diagnosis`

**Excerpt**

Spring Boot logs one startup number and hides four phases behind it. This walks through
turning on the `ApplicationStartup` instrumentation that ships switched off, reading the
step tree by self time rather than total duration — the mistake that makes people optimise
a bean costing 10 ms instead of the one costing 504 — and then puts measured numbers on
component scanning (0.11 ms per class inspected, whether or not it is a bean), on the
silent truncation a 2048-step buffer performs on your recording, and on the JDK 25 AOT
cache, which took 6.93 s to 4.82 s on the companion project without a line of application
code changing.

**Categories**

Java (328), Spring (355)

**Yoast**

- `_yoast_wpseo_title`: Spring Boot Startup Time: A Bean-by-Bean Diagnosis
- `_yoast_wpseo_metadesc`: Turn on Spring Boot's built-in startup instrumentation, read the step tree by self time, and see measured numbers for component scanning, buffer truncation and the JDK 25 AOT cache.
- `_yoast_wpseo_focuskw`: spring boot startup time

**Companion repository**

`asmhatre/spring-boot-demo` → [`spring-boot-startup-time/`](../)

**Jira**

BLOG-618

**Verified against**

Spring Boot 4.1.1 (GA 20 August 2026), Spring Framework 7.0.9, Spring Data JPA 4.1.1,
Hibernate ORM 7.4.5.Final, Tomcat 11.0.24, Micrometer 1.17.1, H2 2.4.240,
Temurin 25.0.4.1+1 LTS, Maven 3.9.11.