Deferred processing mode in PeopleSoft reduces the number of trips to the server by buffering multiple operations and sending them together, rather than making individual server calls for each action. This improves performance by minimizing network overhead.
Deferred processing mode batches up field-level PeopleCode and validation so it runs only when the user actually needs a server round trip (e.g., on save or a button click), rather than firing to the server after every field change. That's why it decreases trips to the server compared to interactive mode, improving performance especially over slower connections.