It maybe possible or not. Becasue the bandwidth is effected on various environment as the shared network status, MCU throughput, retransmittion, and so on.
Mind if I roughly calculated in theory,
For one byte sending time , it needs 3 NIC clock at least. So, To send 3500 bytes, It takes 35003NIC clock at least.
when If the link is 100Mbps, NIC clock is 40ns. If 10Mbps, 400ns.
If 100Mbps, 420us. If 10Mbps, 4.2ms.
If you can copy 3500 bytes data into a Socket Tx Memroy and control the W5300 within the rest time 580us.
But, you should copy and control as fast as possible. because it doesn’t consider the time internal logic processing time that maybe small and 10~20us.