Git Subtree pushes results in a long object. How to avoid this?

Question

I added a subtree to my project as follows:

git subtree add --prefix sites/all/modules \ [e-mail] :ucbdrupal/migrate_hrweb.git master --squash 

I installed these remotes:

 $ git remote -v migrate-hrweb-github [e-mail] :ucbdrupal/migrate_hrweb.git (fetch) migrate-hrweb-github [e-mail] :ucbdrupal/migrate_hrweb.git (push) origin ssh://codeserver.dev.76fc8622-a639-4e1e-873e- [e-mail].76fc8622-a639-4e1e-873e-963cf71fd555 .drush.in:2222/~/repository.git (fetch) origin ssh:// codeserver.dev.76fc8622-a639-4e1e-873e-963cf71fd555@codeserver.d ev.76fc8622- a639-4e1e-873e-963cf71fd555.drush.in:2222/~/repository.git (push) 

Git status does not show changes.

On the main branch, I edit README.md in the subtree directory.

I commit:

 [ bwood@ucbmbp hrweb-ob-js]$ git commit -am "Test edit #4 of hrweb_migrate" [master 6f4b9c1] Test edit #4 of hrweb_migrate 1 file changed, 1 insertion(+) 

I am trying to push this to remote migr-hrweb-github:

 $ git subtree push -P sites/all/modules/migrate_hrweb migrate-hrweb-github master using: migrate-hrweb-github master 

Now I need to wait for the completion of this large number of objects (5 min). The main project is a large Drupal installation. I think every object is counted / filtered:

 1022/ 16200 (1022) [this updates for a while...] 

Finally, I get:

 Counting objects: 8, done. Delta compression using up to 4 threads. Compressing objects: 100% (6/6), done. Writing objects: 100% (6/6), 559 bytes, done. Total 6 (delta 4), reused 0 (delta 0) To [e-mail] :ucbdrupal/migrate_hrweb.git a9c0af1..a6db986 a6db986c0472dbafbd6861f75711a7c509374125 -> master 

How can I avoid this long wait for the account of the object with each commit? (I assume the answer might be related to the 'git subtree section' ...?)