[wglb]

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.

[GalacticDomin8r]

Compiler is also going to make an impact which for me is consistent across both grep binaries.

FreeBSD clang version 6.0.1 as well as -O2

I suspect there are still edge cases where BSD grep is quite a bit slower or not compatible with GNU grep. However with a closer apples to apples comparison there isn't much difference anymore for my usage. Which is a lot of grep use but that is pretty vanilla.

There may also be other OS differences in our comparison. My tests where run against a fairly recent FreeBSD 12-STABLE.