ACLCHECK time increased dramatically after upgrade to Bordermanager 3.9

After the upgrade to bordermanager 3.9 the time that ACLcheck needs to
read the rules has increased from less than a second to 1.10 minutes.
During this time the internetaccess is blocked with a 403 error.
What should I be looking at to find the source of this increase in time
needed to read the rules ?

When I look at the effective rules in imanager I see 53 rules (including 2
surfcontrol category rules), the same as before the upgrade.

When I click effective rules and click on one of the parent containers I
see the following error:
Error: NDS Error -601
(Error -601) The object name entered could not be found in the context
specified. Refer to Help for all listings of possible causes and

The parent containers have no rules specified. I don't know if this is
normal behaviour in this case ?

Kind regards,