The libpcap that is provided with the Sniffer10G 2.0 package supports a pcap_inject method that can maintain lower per-packet overhead than PF_PACKET.
To use this libpcap you must configure your tcpreplay package to use the right libpcap and the right "injection" method (which is pcap_inject), using a configure line such as:
./configure --enable-force-inject --with-libpcap=/opt/snf --enable-dynamic-link