I'd forgotten to upgrade grep on my latest Macbook. In a large source code repo, looking for a fixed string with no wildcards:

osx grep -r:

  real 2m37.786s
  user 2m27.034s
  sys 0m3.958s

ggrep -r:

  real 0m12.842s
  user 0m5.754s
  sys 0m2.825s

which is the difference between something I'd avoid and something I'll use.