I ran each test four times and picked the best result — not my first rodeo — but for the first result I picked the wrong time from my output, which obviously di

I ran each test four times and picked the best result — not my first rodeo — but for the first result I picked the wrong time from my output, which obviously didn't make use of the cache. Here's it again, complete result, added --no-mmap: # ggrep zerogravitas$ for x in {1..4}; do (time ggrep erzg4 k.json >/dev/null); done ggrep erzg4 k.json > /dev/null 1.96s user 0.67s system 99% cpu 2.641 total ggrep erzg4 k.json > /dev/null 1.95s user 0.68s system 99% cpu 2.660 total ggrep erzg4 k.json > /dev/null 2.00s user 0.66s system 99% cpu 2.672 total ggrep erzg4 k.json > /dev/null 1.96s user 0.67s system 98% cpu 2.662 total # rg zerogravitas$ for x in {1..4}; do (time rg erzg4 k.json >/dev/null); done rg erzg4 k.json > /dev/null 1.76s user 1.40s system 99% cpu 3.180 total rg erzg4 k.json > /dev/null 1.77s user 1.31s system 99% cpu 3.088 total rg erzg4 k.json > /dev/null 1.74s user 1.36s system 99% cpu 3.128 total rg erzg4 k.json > /dev/null 1.76s user 1.41s system 97% cpu 3.265 total # rg --no-mmap zerogravitas$ for x in {1..4}; do (time rg erzg4 k.json --no-mmap >/dev/null); done rg erzg4 k.json --no-mmap > /dev/null 0.98s user 0.75s system 99% cpu 1.743 total rg erzg4 k.json --no-mmap > /dev/null 0.99s user 0.75s system 99% cpu 1.740 total rg erzg4 k.json --no-mmap > /dev/null 1.01s user 0.76s system 99% cpu 1.772 total rg erzg4 k.json --no-mmap > /dev/null 0.99s user 0.75s system 99% cpu 1.754 total # rg -j4 zerogravitas$ for x in {1..4}; do (time rg erzg4 k.json -j4 >/dev/null); done rg erzg4 k.json -j4 > /dev/null 1.75s user 1.35s system 98% cpu 3.134 total rg erzg4 k.json -j4 > /dev/null 1.75s user 1.44s system 98% cpu 3.224 total rg erzg4 k.json -j4 > /dev/null 1.80s user 1.38s system 99% cpu 3.204 total rg erzg4 k.json -j4 > /dev/null 1.80s user 1.35s system 99% cpu 3.164 total # rg -j4 --no-mmap zerogravitas$ for x in {1..4}; do (time rg erzg4 k.json -j4 --no-mmap >/dev/null); done rg erzg4 k.json -j4 --no-mmap > /dev/null 0.98s user 0.75s system 99% cpu 1.740 total rg erzg4 k.json -j4 --no-mmap > /dev/null 0.97s user 0.74s system 99% cpu 1.721 total rg erzg4 k.json -j4 --no-mmap > /dev/null 0.99s user 0.75s system 99% cpu 1.752 total rg erzg4 k.json -j4 --no-mmap > /dev/null 0.98s user 0.76s system 99% cpu 1.748 total Sounds like "alias rg=rg --no-mmap" is a good idea on a Mac.