The Elastic APM Java Agent is a free, open-source tool designed to provide insights into application performance and analyze error root causes, supporting distributed tracing particularly useful for service-oriented architectures. While it inevitably introduces some overhead, the agent is designed to minimize impact on application performance through strategies such as running reporting processes on a background thread and reusing objects to reduce memory allocations. The agent's performance can be fine-tuned through configuration options, including adjusting the sample rate of requests recorded and sent to the APM Server, which affects network bandwidth and disk space usage. The agent's overhead in terms of latency is kept minimal by employing efficient data transfer techniques and by processing stack traces asynchronously. Additionally, users can optimize performance by managing the collection of headers, cookies, and stack traces.