diff --git a/addons/web_planner/models/web_planner.py b/addons/web_planner/models/web_planner.py
index 2236486c0f1..15e462428c6 100644
--- a/addons/web_planner/models/web_planner.py
+++ b/addons/web_planner/models/web_planner.py
@@ -62,12 +62,11 @@ class Planner(models.Model):
             params['model'] = 'ir.module.module'
         # setting the module
         if module_name:
-            module = self.env['ir.module.module'].sudo().search([('name', '=', module_name)], limit=1)
-            if module:
-                params['id'] = module.id
+            installed = self.env['ir.module.module']._installed()
+            if module_name in installed:
+                params['id'] = installed[module_name]
         return "/web#%s" % (urlencode(params),)
 
     @api.model
     def is_module_installed(self, module_name=None):
-        count = self.env['ir.module.module'].sudo().search_count([('state', '=', 'installed'), ('name', '=', module_name)])
-        return bool(count)
+        return module_name in self.env['ir.module.module']._installed()
diff --git a/openerp/addons/base/ir/ir_actions.py b/openerp/addons/base/ir/ir_actions.py
index 2b19be7c479..ba2d4097f95 100644
--- a/openerp/addons/base/ir/ir_actions.py
+++ b/openerp/addons/base/ir/ir_actions.py
@@ -18,6 +18,7 @@ from openerp.osv import fields, osv
 from openerp.osv.orm import browse_record
 import openerp.report.interface
 from openerp.report.report_sxw import report_sxw, report_rml
+from openerp.tools import ormcache
 from openerp.tools.safe_eval import safe_eval as eval
 from openerp.tools.translate import _
 import openerp.workflow
@@ -387,6 +388,27 @@ class ir_actions_act_window(osv.osv):
         res_id = dataobj.browse(cr, uid, data_id, context).res_id
         return self.read(cr, uid, [res_id], [], context)[0]
 
+    @openerp.api.model
+    def create(self, vals):
+        self.clear_caches()
+        return super(ir_actions_act_window, self).create(vals)
+
+    @openerp.api.multi
+    def unlink(self):
+        self.clear_caches()
+        return super(ir_actions_act_window, self).unlink()
+
+    @openerp.api.multi
+    def exists(self):
+        ids = self._existing()
+        return self.filtered(lambda rec: rec.id in ids)
+
+    @openerp.api.model
+    @ormcache()
+    def _existing(self):
+        self._cr.execute("SELECT id FROM %s" % self._table)
+        return set(row[0] for row in self._cr.fetchall())
+
 VIEW_TYPES = [
     ('tree', 'Tree'),
     ('form', 'Form'),
diff --git a/openerp/addons/base/module/module.py b/openerp/addons/base/module/module.py
index 50331d0f1e6..db4cbe82069 100644
--- a/openerp/addons/base/module/module.py
+++ b/openerp/addons/base/module/module.py
@@ -29,6 +29,7 @@ import openerp.exceptions
 from openerp import modules, tools
 from openerp.modules.db import create_categories
 from openerp.modules import get_module_resource
+from openerp.tools import ormcache
 from openerp.tools.parse_version import parse_version
 from openerp.tools.translate import _
 from openerp.osv import osv, orm, fields
@@ -328,6 +329,7 @@ class module(osv.osv):
         #if ids_meta:
         #    self.pool.get('ir.model.data').unlink(cr, uid, ids_meta, context)
 
+        self.clear_caches()
         return super(module, self).unlink(cr, uid, ids, context=context)
 
     @staticmethod
@@ -806,6 +808,15 @@ class module(osv.osv):
             if not mod.description:
                 _logger.warning('module %s: description is empty !', mod.name)
 
+    @api.model
+    @ormcache()
+    def _installed(self):
+        """ Return the set of installed modules as a dictionary {name: id} """
+        return {
+            module.name: module.id
+            for module in self.sudo().search([('state', '=', 'installed')])
+        }
+
 
 DEP_STATES = [
     ('uninstallable', 'Uninstallable'),