Unable to shrink repository size

[Robert Dailey <rcdailey.lists@gmail.com>]

I have a git-svn clone that I've been working on which is a full and
complete conversion of our SVN repository at work.

It started out as 1.4GB (git count-objects -v, looking at
'size-pack'). I have run the following script to clean up a directory
in the repo history that I suspect are huge (we had a third party
library checked in that, uncompressed, was about 1.2GB in size):

-------------------------------
files=$@
echo "Removing: $files..."
git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch
$files" -- --all

# remove the temporary history git-filter-branch otherwise leaves
behind for a long time
rm -rf .git/refs/original/ && git reflog expire --expire=now --all &&
git gc --aggressive --prune=now
-------------------------------

Even though I seem to have removed it, the repository size (looking at
'size-pack' again) only went down about 200MB, so it's at 1.2GB now.
There is about 3-5 years of commit history in this repository.

What I'd like to do is somehow hunt down the largest commit (*not*
blob) in the entire history of the repository to hopefully find out
where huge directories have been checked in.

I can't do a search for largest file (which most google results seem
to show to do) since the culprit is really thousands of unnecessary
files checked into a single subdirectory somewhere in history.

Can anyone offer me some advice to help me reduce the size of my repo
further? Thanks.