Even though the source activity executed reasonably fast, it's essential to understand the complexity of the CDC.
In many implementations, CDC can introduce latency, especially when handling large datasets.
Sometimes, the source might have complex joins, aggregations, or other operations that slow down the sink.
If your source and sink are in different regions, I assume you can experience added latency. Maybe in this case the source and the sink need to be in the same region if possible. Also, check that other processes aren't competing for resources