The "old" pf_ring is only meant for packet capture and involves packet copies, so it is several times slower than netmap. There is a newer "Direct Network Access" (DNA) version of pf_ring which avoids copies and has the same performance of netmap, but is much more fragile because in DNA the userspace program writes directly into the NIC registers and rings (so it can crash the entire OS), whereas in netmap the NIC programming is filtered by system calls.