diff --git a/addons/gamification/models/challenge.py b/addons/gamification/models/challenge.py
index ecb4c495d94..d3297a048d3 100644
--- a/addons/gamification/models/challenge.py
+++ b/addons/gamification/models/challenge.py
@@ -240,6 +240,11 @@ class gamification_challenge(osv.Model):
 
         write_res = super(gamification_challenge, self).write(cr, uid, ids, vals, context=context)
 
+        if vals.get('report_message_frequency', 'never') != 'never':
+            # _recompute_challenge_users do not set users for challenges with no reports, subscribing them now
+            for challenge in self.browse(cr, uid, ids, context=context):
+                self.message_subscribe(cr, uid, [challenge.id], [user.partner_id.id for user in challenge.user_ids], context=context)
+
         if vals.get('state') == 'inprogress':
             self._recompute_challenge_users(cr, uid, ids, context=context)
             self._generate_goals_from_challenge(cr, uid, ids, context=context)
@@ -264,6 +269,9 @@ class gamification_challenge(osv.Model):
         - Create the missing goals (eg: modified the challenge to add lines)
         - Update every running challenge
         """
+        if context is None:
+            context = {}
+
         # start scheduled challenges
         planned_challenge_ids = self.search(cr, uid, [
             ('state', '=', 'draft'),
@@ -281,6 +289,9 @@ class gamification_challenge(osv.Model):
         if not ids:
             ids = self.search(cr, uid, [('state', '=', 'inprogress')], context=context)
 
+        # in cron mode, will do intermediate commits
+        # TODO in trunk: replace by parameter
+        context.update({'commit_gamification': True})
         return self._update_all(cr, uid, ids, context=context)
 
     def _update_all(self, cr, uid, ids, context=None):
@@ -355,10 +366,12 @@ class gamification_challenge(osv.Model):
                 if write_op:
                     self.write(cr, uid, [challenge.id], {'user_ids': write_op}, context=context)
 
-                if to_remove_ids:
-                    self.message_unsubscribe_users(cr, uid, [challenge.id], to_remove_ids, context=None)
-                if to_add_ids:
-                    self.message_subscribe_users(cr, uid, [challenge.id], to_add_ids, context=context)
+                # TODO for trunk: use proper parameter
+                if challenge.report_message_frequency != 'never':
+                    if to_remove_ids:
+                        self.message_unsubscribe_users(cr, uid, [challenge.id], to_remove_ids, context=context)
+                    if to_add_ids:
+                        self.message_subscribe_users(cr, uid, [challenge.id], to_add_ids, context=context)
 
         return True
 
@@ -393,9 +406,9 @@ class gamification_challenge(osv.Model):
         :param list(int) ids: the list of challenge concerned"""
 
         goal_obj = self.pool.get('gamification.goal')
-        to_update = []
         for challenge in self.browse(cr, uid, ids, context=context):
             (start_date, end_date) = start_end_date_for_period(challenge.period)
+            to_update = []
 
             # if no periodicity, use challenge dates
             if not start_date and challenge.start_date:
@@ -698,34 +711,35 @@ class gamification_challenge(osv.Model):
             rewarded_users = []
             challenge_ended = end_date == yesterday.strftime(DF) or force
             if challenge.reward_id and challenge_ended or challenge.reward_realtime:
-                for user in challenge.user_ids:
-                    reached_goal_ids = self.pool.get('gamification.goal').search(cr, uid, [
-                        ('challenge_id', '=', challenge.id),
-                        ('user_id', '=', user.id),
-                        ('start_date', '=', start_date),
-                        ('end_date', '=', end_date),
-                        ('state', '=', 'reached')
-                    ], context=context)
-                    if len(reached_goal_ids) == len(challenge.line_ids):
+                # not using start_date as intemportal goals have a start date but no end_date
+                reached_goals = self.pool.get('gamification.goal').read_group(cr, uid, [
+                    ('challenge_id', '=', challenge.id),
+                    ('end_date', '=', end_date),
+                    ('state', '=', 'reached')
+                ], fields=['user_id'], groupby=['user_id'], context=context)
+                for reach_goals_user in reached_goals:
+                    if reach_goals_user['user_id_count'] == len(challenge.line_ids):
                         # the user has succeeded every assigned goal
+                        user_id = reach_goals_user['user_id'][0]
                         if challenge.reward_realtime:
                             badges = self.pool['gamification.badge.user'].search(cr, uid, [
                                 ('challenge_id', '=', challenge.id),
                                 ('badge_id', '=', challenge.reward_id.id),
-                                ('user_id', '=', user.id),
+                                ('user_id', '=', user_id),
                             ], count=True, context=context)
                             if badges > 0:
                                 # has already recieved the badge for this challenge
                                 continue
-                        self.reward_user(cr, uid, user.id, challenge.reward_id.id, challenge.id, context=context)
-                        rewarded_users.append(user)
+                        self.reward_user(cr, uid, user_id, challenge.reward_id.id, challenge.id, context=context)
+                        rewarded_users.append(user_id)
 
             if challenge_ended:
                 # open chatter message
                 message_body = _("The challenge %s is finished." % challenge.name)
 
                 if rewarded_users:
-                    message_body += _("<br/>Reward (badge %s) for every succeeding user was sent to %s." % (challenge.reward_id.name, ", ".join([user.name for user in rewarded_users])))
+                    user_names = self.pool['res.users'].name_get(cr, uid, rewarded_users, context=context)
+                    message_body += _("<br/>Reward (badge %s) for every succeeding user was sent to %s." % (challenge.reward_id.name, ", ".join([name for (user_id, name) in user_names])))
                 else:
                     message_body += _("<br/>Nobody has succeeded to reach every goal, no badge is rewared for this challenge.")
 
diff --git a/addons/gamification/models/goal.py b/addons/gamification/models/goal.py
index af9a763236d..b4a47a0d07a 100644
--- a/addons/gamification/models/goal.py
+++ b/addons/gamification/models/goal.py
@@ -138,7 +138,6 @@ class gamification_goal(osv.Model):
 
     _name = 'gamification.goal'
     _description = 'Gamification goal instance'
-    _inherit = 'mail.thread'
 
     def _get_completion(self, cr, uid, ids, field_name, arg, context=None):
         """Return the percentage of completeness of the goal, between 0 and 100"""
@@ -226,8 +225,7 @@ class gamification_goal(osv.Model):
                 temp_obj = self.pool.get('email.template')
                 template_id = self.pool['ir.model.data'].get_object(cr, uid, 'gamification', 'email_template_goal_reminder', context)
                 body_html = temp_obj.render_template(cr, uid, template_id.body_html, 'gamification.goal', goal.id, context=context)
-
-                self.message_post(cr, uid, goal.id, body=body_html, partner_ids=[goal.user_id.partner_id.id], context=context, subtype='mail.mt_comment')
+                self.pool['mail.thread'].message_post(cr, uid, 0, body=body_html, partner_ids=[goal.user_id.partner_id.id], context=context, subtype='mail.mt_comment')
                 return {'to_update': True}
         return {}
 
@@ -241,9 +239,9 @@ class gamification_goal(osv.Model):
         the target value being reached, the goal is set as failed."""
         if context is None:
             context = {}
+        commit = context.get('commit_gamification', False)
 
         goals_by_definition = {}
-        goals_to_write = {}
         all_goals = {}
         for goal in self.browse(cr, uid, ids, context=context):
             if goal.state in ('draft', 'canceled'):
@@ -251,10 +249,10 @@ class gamification_goal(osv.Model):
                 continue
 
             goals_by_definition.setdefault(goal.definition_id, []).append(goal)
-            goals_to_write[goal.id] = {}
             all_goals[goal.id] = goal
 
         for definition, goals in goals_by_definition.items():
+            goals_to_write = dict((goal.id, {}) for goal in goals)
             if definition.computation_mode == 'manually':
                 for goal in goals:
                     goals_to_write[goal.id].update(self._check_remind_delay(cr, uid, goal, context))
@@ -345,22 +343,24 @@ class gamification_goal(osv.Model):
                         if new_value != goal.current:
                             goals_to_write[goal.id]['current'] = new_value
 
-        for goal_id, value in goals_to_write.items():
-            if not value:
-                continue
-            goal = all_goals[goal_id]
+            for goal_id, value in goals_to_write.items():
+                if not value:
+                    continue
+                goal = all_goals[goal_id]
 
-            # check goal target reached
-            if (goal.definition_condition == 'higher' and value.get('current', goal.current) >= goal.target_goal) \
-              or (goal.definition_condition == 'lower' and value.get('current', goal.current) <= goal.target_goal):
-                value['state'] = 'reached'
+                # check goal target reached
+                if (goal.definition_condition == 'higher' and value.get('current', goal.current) >= goal.target_goal) \
+                  or (goal.definition_condition == 'lower' and value.get('current', goal.current) <= goal.target_goal):
+                    value['state'] = 'reached'
 
-            # check goal failure
-            elif goal.end_date and fields.date.today() > goal.end_date:
-                value['state'] = 'failed'
-                value['closed'] = True
-            if value:
-                self.write(cr, uid, [goal.id], value, context=context)
+                # check goal failure
+                elif goal.end_date and fields.date.today() > goal.end_date:
+                    value['state'] = 'failed'
+                    value['closed'] = True
+                if value:
+                    self.write(cr, uid, [goal.id], value, context=context)
+            if commit:
+                cr.commit()
         return True
 
     def action_start(self, cr, uid, ids, context=None):
diff --git a/addons/gamification/views/goal.xml b/addons/gamification/views/goal.xml
index 528d5db0511..884467404ce 100644
--- a/addons/gamification/views/goal.xml
+++ b/addons/gamification/views/goal.xml
@@ -86,10 +86,6 @@
                             </group>
                         </group>
                     </sheet>
-                    <div class="oe_chatter">
-                        <field name="message_follower_ids" widget="mail_followers"/>
-                        <field name="message_ids" widget="mail_thread"/>
-                    </div>
                 </form>
             </field>
         </record>