By default, Splunk AppDynamics collects a snapshot every 10 minutes.

Navigate to Configuration > Slow Transaction Thresholds. You can modify this default in the Slow Transaction Thresholds configuration page.

The value will apply to subsequently created business transactions, but if you check Apply to all Existing Business Transactions, all existing business transactions are affected by the change.

If you have a high load production environment, do not use low values for snapshot collection. You must configure the collection on a very frequent basis. When there are thousands or millions of requests per minute, collecting snapshots too frequently may result in many extra and useless snapshots. Either turn off the periodic snapshots and apply to all Business Transactions, or choose a very conservative (high) rate depending on the expected load. For example, if you have a high load on the application, choose every 1000th executions or every 20 minutes, depending on the load pattern.