I can confirm that mounting /run in the chroot significantly speeds up `update-grub' as well as lvm scan commands.
I'm bootstrapping a new virtual machine from a live disk and `update-grub` was running in the chroot. In a separate terminal, I entered the following command and `update-grub` finished nearly instantly: $ sudo mount --bind /run /mnt/target/run This is not a solution to the bug, but it's certainly a viable workaround.
