run git gc on all your dirs!

gitGc.py

import sys
import os
from subprocess import Popen, PIPE

myWorkDir = '/home/jpmcgrady/workspace'

def runGc(dirNameIn):
    os.chdir(dirNameIn)
    try:
        output = Popen(["git", "gc"], stdout=PIPE).communicate()[0]
        if output: print output
        return True
    except:
        return False

if __name__ == '__main__':
    myDirs = ["%s/%s"%(myWorkDir,myDir) for myDir in os.listdir(myWorkDir) if os.path.isdir("%s/%s"%(myWorkDir,myDir))]
    print myDirs
    for thisDir in myDirs:
        print "%s->%s"%(thisDir, runGc(thisDir))