Grant ROLE performance issue

Hi ,

I am seeing a major performance difference when running a grant to a role vs grant to a user can any one explain why this is happening and if there is a way to improve the performance of grants to a role.

GRANT SELECT, INSERT, UPDATE, DELETE ON TEST.T1 TO USER FRED@
Takes 6ms

GRANT SELECT, INSERT, UPDATE, DELETE ON TEST.T1 TO ROLE TESTER@
Takes 1s 466 ms


Windows 7

db2level DB21085I Instance "DB2" uses "64" bits and DB2 code release "SQL09076" with level identifier "08070107".
Informational tokens are "DB2 v9.7.600.458", "s120629", "IP23416", and Fix Pack
"6".