To adjust the App Visibility agent performance overhead, modify the number of sampled, or persisted, requests.
The accuracy of metrics is affected by the sampling rate; a lower sampling rate means lower overhead but also lower accuracy.
Begin sampling requests at the default value, 100%. Usually, this rate does not noticeably impact application performance, but if traffic is very high and application performance is negatively impacted, lower the sampling rate. In a high-traffic situation, reducing the sample rate does not considerably reduce the accuracy.
You can alsoso that transactions with specific headers are always persisted, regardless of the sampling rate.
The agent reads header types from the Agent Policy. For each request type (regardless of sampling), the agent collects the HTTP headers and their values. If the header exists, the agent persists the request, and the App Visibility collector adds the request to the database.