Replay performance impacts

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When considering enabling Session Replay, it’s important to understand how Session Replay might influence your app’s speed and overall performance.

Effects of data transmission

To conserve network bandwidth, Pendo’s standard data collection and transmission process compresses and transmits data every two minutes.

When you enable Session Replay for an application, data transmission becomes more frequent, occurring as often as every five seconds. This increase is due to the additional data we capture, such as mouse movement events.

Depending on the complexity of the interactions captured in a replay, particularly if your page has a high CPU load, Session Replay could potentially impact performance.

Similarly, when visitors access your app on a mobile device, there’s a potential impact on battery life. If you receive reports of such issues, consider excluding these visitors from capture using the most recent device type does not equal mobile segment rule on the Replay Settings page.

Web workers for enhanced performance

To minimize the risk of compromising your app’s performance during replay captures, we employ web workers. Web workers are background scripts that handle resource-intensive tasks, which prevents your app from slowing down.

Pendo offloads replay captures to these web workers to reduce the potential impact on your app’s main thread. This ensures that we can capture visitor interactions without impacting your app’s responsiveness.

If you have a Content Security Policy (CSP) configuration for Pendo, it’s crucial to update it to avoid potential conflicts with web workers and ensure your app’s performance remains unaffected. For more details, see CSP configuration.

Tip: To alleviate potential performance concerns, we recommend enabling Session Replay for a smaller set of internal users so that you can monitor performance effectively and make informed decisions. To learn more, see Segmentation.

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