enabled_emulation greatly reduces keystone performance

When enabled_emulation is enabled, the performance of Keystone suffers greatly. I see a approx 4x slower result when it is enabled. I discussed this some in my blog post (http://www.mattfischer.com/blog/?p=561) and was asked to file a bug by Yuriy. Here are some results. Each query had about 20 results, but I've removed them since it has private emails and what not.

enabled_emulation off:

root@j1:~# time keystone user-list
+--------------+--------------+---------+---------------------------+
| id | name | enabled | email |
+--------------+--------------+---------+---------------------------+
| admin | admin | True | |
...
+--------------+--------------+---------+---------------------------+

real 0m2.767s
user 0m0.380s
sys 0m0.284s

enabled_emulation on:

root@j1:~# time keystone user-list
+--------------+--------------+---------+---------------------------+
| id | name | enabled | email |
+--------------+--------------+---------+---------------------------+
| admin | admin | True | |
...
+--------------+--------------+---------+---------------------------+

real 0m9.099s
user 0m0.508s
sys 0m0.084s

Similar results happen for tenant enabled emulation.

My LDAP box is a Free IPA server running on CentOS if that matters.

I'm running Keystone 2013.2.2-0ubuntu1~cloud0