Comment by burntsushi

Look at ag's issue tracker. There are some very critical bugs. You might be impacted by them and not even know it.

As for perf, it's not hard to witness a 10x improvement that you'll actually feel. On my checkout of the Linux kernel:

    $ (time rg -wi '\w+(PM_RESUME|LINK_REQ)') | wc -l

    real    0.114
    user    0.547
    sys     0.543
    maxmem  29 MB
    faults  0
    444

    $ (time ag -wi '\w+(PM_RESUME|LINK_REQ)') | wc -l

    real    0.949
    user    6.618
    sys     0.805
    maxmem  65 MB
    faults  0
    444

Or even basic queries can have a pretty big difference. In my checkout of the Chromium repository:

    $ (time rg Openbox) | wc -l

    real    0.296
    user    1.349
    sys     1.950
    maxmem  71 MB
    faults  0
    11

    $ (time ag Openbox) | wc -l

    real    1.528
    user    1.849
    sys     8.285
    maxmem  29 MB
    faults  0
    11

Or even more basic. You might search a file that is "too big" for ag:

    $ time ag '^\w{42}$' full.txt
    ERR: Skipping full.txt: pcre_exec() can't handle files larger than 2147483647 bytes.