Hi,

In DISTINCT mode, the default for the internal buffer size is a potentially unlimited buffer (while, in MERGE mode, the default is a buffer of size 1).
Having a large buffer for an item can be useful when updates for the item may come in bursts, so that all updates in the burst are queued and dispatched one at a time. This, however, is true only provided that the mean update frequency from the Data Adapter is much lower than the frequency limit imposed for the item. Otherwise, the buffer is always full and this causes latencies.
So, try lowering the buffer size, either in the Metadata Adapter configuration or in the client Table configuration.

Just in case, consider that the main differences between the MERGE and DISTINCT modes are about the interpretation of the updates coming from the Data Adapter, rather than about update delivery.
In particular, missing fields from the updates received from the Data Adapter are treated as unchanged fields in MERGE and as null fields in DISTINCT.
Moreover, the snapshot is maintained as the last (merged) update in MERGE mode and as a historical list of updates in DISTINCT.
So, make sure that the DISTINCT mode is suitable for your case.

Dario