terrible cloning performance for user, not root

[Lasse Kliemann]

on several of my virtual servers, cloning within the filesystem (no network)
gives reasonable performance as root, but absolutely breaks down as a normal
user. for example, cloning the python repository takes 20 seconds as root
but something between 3 to 10 minutes as normal user. i tried to figure out
any differences in the configuration user vs. root (ulimit, quota), but to
no avail; there appear to be no differences. also i could not find another
application showing the same performance difference, in particular git,
rsync, and tar work fine. i also tested different distributions (latest
ubuntu and centos in particular), and they all show the same problem. i
already sent a request to the vserver provider, but since hg is the only
application showing this problem so far, i am pessimistic about their
ability or willingness to resolve it.

could anyone give a hint what to look out for? anyone noticed anything
similar before? thanks a lot.