--- loncom/interface/lonnavmaps.pm	2011/12/28 04:11:05	1.478
+++ loncom/interface/lonnavmaps.pm	2012/02/17 19:25:57	1.479
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Navigate Maps Handler
 #
-# $Id: lonnavmaps.pm,v 1.478 2011/12/28 04:11:05 raeburn Exp $
+# $Id: lonnavmaps.pm,v 1.479 2012/02/17 19:25:57 raeburn Exp $
 
 #
 # Copyright Michigan State University Board of Trustees
@@ -3614,6 +3614,8 @@ sub new {
     $self->{NAV_MAP}->{RESOURCE_CACHE}->{$self->{ID}} = $self;
     $self->{RESOURCE_ERROR} = 0;
 
+    $self->{DUEDATE_CACHE} = undef;
+
     # A hash that can be used by two-pass algorithms to store data
     # about this resource in. Not used by the resource object
     # directly.
@@ -4252,6 +4254,9 @@ sub checkedin {
 
 sub duedate {
     (my $self, my $part) = @_;
+    if (defined ($self->{DUEDATE_CACHE}->{$part})) {
+        return $self->{DUEDATE_CACHE}->{$part};
+    }
     my $date;
     my @interval=$self->parmval("interval", $part);
     my $due_date=$self->parmval("duedate", $part);
@@ -4268,6 +4273,7 @@ sub duedate {
     } else {
 	$date = $due_date;
     }
+    $self->{DUEDATE_CACHE}->{$part} = $date;
     return $date;
 }
 sub handgrade {