title: git push is very slow for a huge repo
body: <p>I am having the same issue as in - <a href="https://stackoverflow.com/questions/29118876/git-push-is-very-slow-for-a-branch">git push is very slow for a branch</a>
  but the answer there doesn't fit my situation.</p>
  
  <p>I am working against a corporate GitHub with a very large repo. My process is as follows:</p>
  
  <p>1) Pull from master</p>
  
  <p>2) Create new branch</p>
  
  <p>3) Commit </p>
  
  <p>4) Push the branch to create a pull request.</p>
  
  <p>When pushing the branch on (4) it wants to write over 1,000,000 objects which take about 3gb when the commit I made was to change only 1 line.</p>
  
  <p>If I go to the GitHub UI and create a branch with the same name as in (2) from the UI, then push into that branch, the push takes less than a second. Needless to say that the changes between master and my branch are very minor (no big file added or deleted).</p>
  
  <p><strong>What can I do to make Git push only the relevant data and not the entire repo?</strong></p>
  
  <p>Git on Windows ver 2.17.0</p>