Hi @trantam_cdt92, thanks for reporting this.
If it is possible, can you send a zipped PCAP file? I would like to know which party causes the 60 ms delay.
It can also be useful to do the same test with a different TCP client like eg. ncat (nc or netcat).
When possible, you could also try to send 2 full packets, each one carrying 1460 bytes, just adding zeros to your send buffer. See if that makes a difference.