I found this trying to store a massive number of files(350k+) in a repo. Yes, store. Laughs.
$ time git add .
git add . 333.67s user 244.26s system 14% cpu 1:06:48.63 total
The following extracts from the Bitbucket documentation are quite interesting.
When you work with a DVCS repository cloning, pushing, you are working with the entire repository and all of its history. In practice, once your repository gets larger than 500MB, you might start seeing issues.
... 94% of Bitbucket customers have repositories that are under 500MB. Both the Linux Kernel and Android are under 900MB.
The recommended solution on that page is to split your project into smaller chunks.