--- loncom/localize/lonlocal.pm	2009/04/16 15:51:42	1.57
+++ loncom/localize/lonlocal.pm	2009/05/06 19:25:49	1.59
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Localization routines
 #
-# $Id: lonlocal.pm,v 1.57 2009/04/16 15:51:42 www Exp $
+# $Id: lonlocal.pm,v 1.59 2009/05/06 19:25:49 droeschl Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -395,6 +395,7 @@ sub gettimezone {
 
 sub locallocaltime {
     my ($thistime,$timezone) = @_;
+
     if (!defined($thistime) || $thistime eq '') {
 	return &mt('Never');
     }
@@ -408,7 +409,16 @@ sub locallocaltime {
     }
 
     my $dt = DateTime->from_epoch(epoch => $thistime)
-                     ->set_time_zone(&gettimezone($timezone));
+                     ->set_time_zone(gettimezone($timezone));
+
+    # TimeZone tries to determine the 'local' timezone from $ENV{TZ} if this
+    # fails it searches through various system files. Under certain
+    # circumstances this is an extremly expensive operation.
+    # So after the first run we store the timezone in $ENV{TZ} to significantly
+    # speed up future lookups. 
+    $ENV{TZ} = $dt->time_zone()->name() 
+        if (! $ENV{TZ} && gettimezone($timezone) eq 'local');
+
     if ((&current_language=~/^en/) || (!$lh)) {
 
 	return $dt->strftime("%a %b %e %I:%M:%S %P %Y (%Z)");