Hi Lidan,

The size of messages you have experimented is actually the typical size of TCP packets sent by Lightstreamer and it is not affected by sendbuf setting. But increasing the sendbuf value in order to allow it to contain more than one TCP packet, it allow to the TCP protocol to send more packets at once, without waiting the ack reply. I think that it was the waiting for ack reply of each packet that raised your issue.

1. We expect no deterioration in terms of performance with values of sendbuf wider, quite the opposite. However, in the factory configuration and we generally recommend a low value in order to early detect network issues and then take recovery actions as soon as possible.
2. Send larger packets (and thus reduce roundtrips) would be even better but we know that the TCP does not impose a roundtrip for each packet and so we were confident that even with a larger sendbuf the situation would be improved.
Alternatively there would be a client-side solution which involves to manage different clients in different ways. But this requires that each client is able to recognize the case to handle independently. Please let me know if I should go deeper on this.

Regards,
Giuseppe