I committed a couple of big binary files, which eventually really slowed down Git.

This is how you find them, and delete them:

Script (will show top 10 biggest files):

#!/bin/bash
#set -x

# Shows you the largest objects in your repo's pack file.
# Written for osx.
# @see http://bit.ly/UmpwkV/
# @author Antony Stubbs

# set the internal field separator to line break, 
# so that we can iterate easily over the verify-pack output
IFS=$'\n';

# list all objects including their size, sort by size, take top 10
objects=`git verify-pack -v .git/objects/pack/pack-*.idx | \
 grep -v chain | sort -k3nr | head`

echo "All sizes are in kB's. The pack column is the size of the object, \
 compressed, inside the pack file."

output="size,pack,SHA,location"
for y in $objects
do
# extract the size in bytes
size=$((`echo $y | cut -f 5 -d ' '`/1024))
# extract the compressed size in bytes
compressedSize=$((`echo $y | cut -f 6 -d ' '`/1024))
# extract the SHA
sha=`echo $y | cut -f 1 -d ' '`
# find the objects location in the repository tree
other=`git rev-list --all --objects | grep $sha`
#lineBreak=`echo -e "\n"`
output="${output}\n${size},${compressedSize},${other}"
done

echo -e $output | column -t -s ', '

And then:

• git filter-branch --force --index-filter \
'git rm --cached --ignore-unmatch some/file/you/dont/want' \
--prune-empty --tag-name-filter cat -- --all
• git push origin master --force
• everywhere else: git pull --rebase