metadata repository using exp vs expdp

10.2.0.2 EE, aix5.2 64bit

I'm implenting a metadata repository to track changes in the database and wanted to try to use datapump instead of export but when I tried to switch I found that datapump took about 3 times the amount of time to do the export. I've searched metalink and can't find any bugs related specifically to content=metadata_only. Has anyone else experienced this? I'm wondering if it isn't something specific about the various schemas in my database that is causing the problems.

Here are the parameters I used for each.

export:
DIRECT=y
FILE=exp_wasdev_meta_041508_11.dmp
FULL=y
COMPRESS=n
ROWS=n
INDEXES=y
CONSTRAINTS=y
LOG=/out/oracle/export/nightly/exp_wasdev_meta.log

datapump:
$OHOME/bin/expdp user/pwd
content=metadata_only
full=y
directory=DATA_PUMP_DIR
dumpfile=tst%U.dmp
parallel=4 Received on Thu Apr 24 2008 - 14:17:11 CDT