title: Get time of last git commit quickly
body: <p>I have an issue of getting time of last commit quickly.
  I am on version 2.32.0.windows.2 so I should have all the core graph functionality, I even manually enabled it with:</p>
  <pre><code>git config --global core.commitGraph true
  git config --global gc.writeCommitGraph true
  git commit-graph write
  </code></pre>
  <p>Still for me the show and log ways of getting last commit time are very slow.</p>
  <blockquote>
  <p>time git show -s --format=%ci</p>
  <p>2021-12-01 18:55:17 +0100</p>
  <p>real    0m1.410s</p>
  <p>user    0m0.015s</p>
  <p>sys     0m0.015s</p>
  </blockquote>
  <blockquote>
  <p>time git log -1 --date=short --pretty=format:%ci</p>
  <p>2021-12-01 18:55:17&gt; +0100</p>
  <p>real    0m1.349s</p>
  <p>user    0m0.000s</p>
  <p>sys     0m0.031s</p>
  </blockquote>
  <p>P.S. I know 1.4 seconds does not seem like a lot, but for me it is, for some other reasons this is executed many times in my project.</p>
  <p>EDIT: this is git trace:</p>
  <blockquote>
  <p>git log -1 --date=short --pretty=format:%ci</p>
  <p>18:57:13.743566 exec-cmd.c:237          trace: resolved executable
  dir: C:/Program Files/Git/mingw64/bin</p>
  <p>18:57:13.749988 git.c:455               trace: built-in: git log -1
  --date=short '--pretty=format:%ci'</p>
  <p>18:57:13.766512 run-command.c:668       trace: run_command: unset
  GIT_PAGER_IN_USE; LESS=FRX LV=-c 'diff-so-fancy | less --tabs=4 -RFX'</p>
  <p>18:57:14.816139 exec-cmd.c:237          trace: resolved executable
  dir: C:/Program Files/Git/mingw64/libexec/git-core</p>
  <p>18:57:14.820048 git.c:455               trace: built-in: git config
  --list</p>
  <p>2021-12-03 09:50:40 +0100</p>
  <p>18:57:15.177615 exec-cmd.c:237          trace: resolved executable
  dir: C:/Program Files/Git/mingw64/bin</p>
  <p>18:57:15.182528 git.c:455               trace: built-in: git config
  --bool core.sparseCheckout</p>
  </blockquote>