Our Spring Boot API responded in around 150 ms during development.
But once the system went live and real users started hitting the endpoint, response time suddenly jumped to almost 3 seconds.
No errors.
No exceptions.
Just a slow API.
After profiling the application using tools like Java Flight Recorder, VisualVM, and YourKit, along with analyzing database queries, system logs, and Spring Boot Actuator traces, we identified several small bottlenecks across different layers of the system that were collectively impacting response time.
Fixing them step by step reduced the response time from 3 seconds to about 200 ms.
⚡ Production response time: 3.1 seconds
🚀 After optimization: 200 ms
Here are the 10 improvements that made the biggest difference.
What’s the worst API performance issue you’ve encountered in production?