As mentioned earlier, the product is architected already to ensure minimal intrusion and impact. Still there are some things you can try:
- Turn on supplemental logging only for the tables you want to capture changes
- Throttle the frequency in which you read changes from the Oracle log, depending on database activity pattern throughout the day
- Throttle the Oracle user that the CDC Service is using by assigning that user to a lower priority resource plan on the source Oracle instance.