grit://cooking/bench/history/reword@synth-10k

grit history · reword @synth-10k

History reword vs git history reword or scripted rebase

repo: 10,000-file synthetic repository; canonical cached shape, scenario variants documented by the runner · 10,000 files · 1,000 commits · 800 refs

$ grit-bench daily --only history/reword@synth-10k2026-10-27 · grit 8dbc58e77 · git version 2.43.0

tool	median	min	max	runs	peak memory
git	6.39 s	6.26 s	6.40 s	5	28 MB
grit	129 ms	128 ms	131 ms	5	23 MB

grit is 49× fastermemory: 1.2× less

every timed run (log scale)

git

grit

102 ms8.06 s

How it's measured

before each run

grit-bench prepare-history-rewrite --git git

git runs

$ set -eu; GIT_CONFIG_NOSYSTEM=1 GIT_CONFIG_GLOBAL='/tmp/grit-bench-global-config' GIT_CONFIG_SYSTEM=/dev/null GIT_AUTHOR_NAME=Bench GIT_AUTHOR_EMAIL=b@example.com GIT_COMMITTER_NAME=Bench GIT_COMMITTER_EMAIL=b@example.com GIT_COMMITTER_DATE='1700000100 +0000' ./.grit-bench/git-reword-rebase.sh >/dev/null

grit runs

$ set -eu; grit history reword HEAD~1000 -m 'grit-bench history rewrite message' >/dev/null

Where the time goesone extra traced run per tool, outside the timed runs

git · median run 6.39 s

index: do_write_index ×1005

2.89 s

unpack_trees: unpack_trees ×2006

1.42 s

merge: checkout ×1000

1.34 s

unpack_trees: traverse_trees ×2006

1.05 s

index: do_read_index ×1004

254 ms

index: refresh ×5

109 ms

cache_tree: update ×1002

98 ms

merge: incore_nonrecursive ×1000

73 ms

run: git commit

46 ms

merge: process_entries ×3000

44 ms

cache_tree: read ×1004

25 ms

merge: collect_merge_info ×1000

21 ms

cache_tree: write ×1005

21 ms

merge: write_auto_merge ×1000

18 ms

merge: merge_start ×1000

12 ms

index: preload ×6

12 ms

merge: traverse_trees ×1000

12 ms

status: print

7.7 ms

merge: plist ×3000

5.3 ms

merge: allocate/init ×1000

4.0 ms

grit · median run 129 ms

grit.revwalk.setup

40 ms

grit.index.read ×4

3.2 ms

grit.repository.open ×2

0.4 ms

grit.config.load ×4

0.2 ms

grit.pack.index.open

0.0 ms

grit.diff.tree ×2

0.0 ms

Every day8 days

date	grit commit	git	grit	grit vs git	grit peak
2026-10-27	8dbc58e77	6.39 s	129 ms	49× faster	23 MB
2026-10-26	c7cf2c443	—	fail	—	—
2026-10-25	2824ad391	6.36 s	146 ms	44× faster	22 MB
2026-10-24	157a05dde	6.59 s	158 ms	42× faster	45 MB
2026-10-23	bddf92f86	6.36 s	163 ms	39× faster	45 MB
2026-10-22	4c131b942	6.22 s	154 ms	40× faster	45 MB
2026-10-21	d4844e92a	6.09 s	151 ms	40× faster	45 MB
2026-10-20	4754ad0b9	6.38 s	150 ms	42× faster	44 MB