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# /usr/bin/grep -V grep (BSD grep) 2.6.0-FreeBSD root@m6600:~ # /usr/local/bin/grep -V grep (GNU grep) 3.3 Copyright (C) 2018 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Written by Mike Haertel and others; see <https://git.sv.gnu.org/cgit/grep.git/tree/AUTHORS>. root@m6600:~ # /usr/bin/time /usr/bin/grep X-User-Agent packetdump.pcap -c 60 0.54 real 0.45 user 0.07 sys root@m6600:~ # /usr/bin/time /usr/bin/grep X-User-Agent packetdump.pcap -c 60 0.54 real 0.44 user 0.08 sys root@m6600:~ # /usr/bin/time /usr/bin/grep X-User-Agent packetdump.pcap -c 60 0.54 real 0.41 user 0.11 sys root@m6600:~ # /usr/bin/time /usr/local/bin/grep X-User-Agent packetdump.pcap -c 60 0.58 real 0.49 user 0.08 sys root@m6600:~ # /usr/bin/time /usr/local/bin/grep X-User-Agent packetdump.pcap -c 60 0.60 real 0.48 user 0.11 sys root@m6600:~ # /usr/bin/time /usr/local/bin/grep X-User-Agent packetdump.pcap -c 60 0.59 real 0.50 user 0.08 sys root@m6600:~ # du -h -s packetdump.pcap 225M packetdump.pcap

That is a very good point. Taking this better approach, here is what I get on my (not updated grep) system:

    wgl:$ /usr/bin/grep --version
    /usr/bin/grep --version
    grep (BSD grep) 2.5.1-FreeBSD
    
    wgl:$ /usr/local/bin/ggrep --version
    /usr/local/bin/ggrep --version
    ggrep (GNU grep) 3.3
    Packaged by Homebrew
    Copyright (C) 2018 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.
    
    Written by Mike Haertel and others; see
    <https://git.sv.gnu.org/cgit/grep.git/tree/AUTHORS>.
    
    wgl:$ /usr/bin/time /usr/local/bin/ggrep LiteonTe really-big.text | wc -l
    /usr/bin/time /usr/local/bin/ggrep LiteonTe really-big.text | wc -l
            2.30 real         1.04 user         0.67 sys
        1228
    wgl:$ /usr/bin/time /usr/bin/grep LiteonTe really-big.text | wc -l
    /usr/bin/time /usr/bin/grep LiteonTe really-big.text | wc -l
            5.65 real         5.30 user         0.33 sys
        1228
    wgl:$ /usr/bin/time /usr/local/bin/ggrep LiteonTe really-big.text >/dev/null
    /usr/bin/time /usr/local/bin/ggrep LiteonTe really-big.text >/dev/null
            0.05 real         0.03 user         0.01 sys
    wgl:$ /usr/bin/time /usr/bin/grep LiteonTe really-big.text >/dev/null
    /usr/bin/time /usr/bin/grep LiteonTe really-big.text >/dev/null
            6.50 real         5.71 user         0.58 sys
    wgl:$ /usr/bin/time /usr/local/bin/ggrep LiteonTe really-big.text -c
    /usr/bin/time /usr/local/bin/ggrep LiteonTe really-big.text -c
    1228
            2.33 real         1.05 user         0.69 sys
    wgl:$ /usr/bin/time /usr/bin/grep LiteonTe really-big.text -c
    /usr/bin/time /usr/bin/grep LiteonTe really-big.text -c
    1228
            5.37 real         5.05 user         0.31 sys

The wc -l is clearly polluting the result. However, I suspect that the >/dev/null is as well. But in the worst case, I see a halving of time over the old grep (edited), which correlates with my most common use of grep in looking through source files.