Anecdotally, Using NFS with Vagrant / Virtualbox instead of the default Virtualbox shared folder speeds up things drastically. Add the following line in your Vagrantfile to test it out:
config.vm.share_folder "/vagrant", "/vagrant", "./", :nfs => true
Also, tweaking the DNS settings seems to help:
vb.customize ["modifyvm", :id, "--natdnshostresolver1", "off"]
vb.customize ["modifyvm", :id, "--natdnsproxy1", "off"]