USER_TAB_PARTITIONS Query Runs Incredibly Slow

I seem to be seeing incredibly slow (5-10 seconds) to run a query against USER_TAB_PARTITIONS (Oracle) intermittently. When I do an explain plan on :

SELECT * FROM USER_TAB_PARTITIONS
WHERE TABLE_NAME='MY_TABLE'

One of the steps shows a Nested Loops/Merge Join (Option = CARTESIAN) operation against TABPART$. The TABPART$ system table shows it has been analyzed in the last day. Is there a known problem with 11.2 and USER_TAB_PARTITIONS?

By the way, I am running Oracle v11.2.0.1