diff --git a/classes/Notice.php b/classes/Notice.php
index de5104fdbb..46e1dca35e 100644
--- a/classes/Notice.php
+++ b/classes/Notice.php
@@ -1236,10 +1236,16 @@ class Notice extends Memcached_DataObject
 
     function asActivity($cur = null, $source = false)
     {
+        $act = self::cacheGet('notice:as-activity:'.$this->id);
+
+        if (!empty($act)) {
+            return $act;
+        }
+
         $act = new Activity();
 	
         if (Event::handle('StartNoticeAsActivity', array($this, &$act))) {
-	    
+
             $profile = $this->getProfile();
 	    
             $act->actor     = ActivityObject::fromProfile($profile);
@@ -1400,6 +1406,8 @@ class Notice extends Memcached_DataObject
             Event::handle('EndNoticeAsActivity', array($this, &$act));
         }
 	
+        self::cacheSet('notice:as-activity:'.$this->id, $act);
+
         return $act;
     }
 
diff --git a/lib/activity.php b/lib/activity.php
index e29bc1a25d..712800817c 100644
--- a/lib/activity.php
+++ b/lib/activity.php
@@ -329,6 +329,14 @@ class Activity
 
     function asString($namespace=false, $author=true)
     {
+        $c = Cache::instance();
+
+        $str = $c->get('activity:as-string:'.Cache::keyize($this->id));
+
+        if (!empty($str)) {
+            return $str;
+        }
+
         $xs = new XMLStringer(true);
 
         if ($namespace) {
@@ -549,7 +557,11 @@ class Activity
 
         $xs->elementEnd('entry');
 
-        return $xs->getString();
+        $str = $xs->getString();
+	
+        $c->set('activity:as-string:'.Cache::keyize($this->id), $str);
+	
+        return $str;
     }
 
     private function _child($element, $tag, $namespace=self::SPEC)