Right now cloning/refreshing a repository often spends a fair amount of its time in the 'Counting objects' stage. Since git 2.0 git has a 'bitmap index' feature for packs. I wonder if that could be enabled on gitmaster/git.pg.o? Saves both time and CPU.
We do pretty strongly want to stick to the packaged versions of git (and other software) to keep our work at reasonable levels. And right now,. only 1.7 is packaged for Debian Wheezy which is what we run. 2.0 isn't even available in backports. However, it will become 2.1 once we can migrate to Jessie, but it's not released yet.
So unless it's something really critical, which I don't think it is (though it does sound like a nice convenience), I would suggest we wait until we go to Jessie, and then enable it.
# enable it everywhere git config --global pack.writebitmaps on git config --global pack.writeBitmapHashCache on git config --global pack.threads 0 # make gc/repack faster, autodetect cpus
# and write it by repacking git gc --aggressive --no-prune
Is that something that would have to be done in a cronjob repeatedly, or are you saying you have to run that once and then it'll be enabled for the future?