High User I/O in 11g vs 10g, bug?

Do you think I am experiencing a bug in 11g? When I run a simple query to view the free space on my tablespaces there is high user I/O against the database. The query takes 2 minutes to run in 11g however in my 10g database it only takes 1 second. This same issue can be reproduced/compared in my testing 11g/10g environments.

This slowness also occurs if I use a tool (DBartisan) to view the tablespaces in the 11g database)

Test query:

SELECT TABLESPACE_NAME,SUM(BYTES)/1024/1024/1024 "FREE SPACE(GB)"
FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME

Database: Enterprise Edition Release 11.2.0.3.6 single-instance using ASM