Deduplication in action
=======================

$ du -sch .git
216K    .git
216K    total

$ git checkout many-files
Switched to branch 'many-files'
$ du -sch .
176M    .
176M    total

You may want to try that checkout in /dev/shm, it's much faster. ;P

Command used to create the files (I didn't actually create them):
for-loop i=00001,...
    git update-index --add --cacheinfo 0644 78981922613b2afb6025042ff6bd878ac1994e85 a$i

where 7898192... is the SHA1 of a blob containing just "a" and a newline.