Selective Acknowledgment allows individual TCP packets to be resent without re-sending the whole buffer window.  This is described in RFC2018.  My former employer, Ethersat of Salt Lake City, is gone now and I no-longer have telnet access to PP or NMS.  If I did, I would type:
sysctl -a | grep sack
sysctl -a | grep 2018

replies like this would indicate probably yes.
net.ipv4.tcp_dsack = 1
net.ipv4.tcp_sack = 1

The results, along with the software revision code, might lead us all to higher performance.