In TCP client mode (at least) W5200 does not send two packets with ‘data payload length’ <= TCP::MTU without an interleaved ACK from the server!
But in this configuration, if TCP::MTU < ‘data payload length’ <= 2×TCP::MTU, W5200 will send a first packet of length TCP::MTU immediately followed by a second packet with the remaining payload, without waiting for an ACK. On this second packet the server will send ACK immediately, as expected.
So sending small TCP packets is extremely slow, as most server will only acknowledge after 200 milliseconds.
Is there a way to “force” W5200 not to wait for an ACK before sending the second small packet???