diff --git a/odoo/addons/base/models/ir_actions.py b/odoo/addons/base/models/ir_actions.py
index d36eb59e4ff..7957510e502 100644
--- a/odoo/addons/base/models/ir_actions.py
+++ b/odoo/addons/base/models/ir_actions.py
@@ -463,7 +463,7 @@ class IrActionsServer(models.Model):
     sequence = fields.Integer(default=5,
                               help="When dealing with multiple actions, the execution order is "
                                    "based on the sequence. Low number means high priority.")
-    model_id = fields.Many2one('ir.model', string='Model', required=True, ondelete='cascade',
+    model_id = fields.Many2one('ir.model', string='Model', required=True, ondelete='cascade', index=True,
                                help="Model on which the server action runs.")
     model_name = fields.Char(related='model_id.model', string='Model Name', readonly=True, store=True)
     # Python code
diff --git a/odoo/addons/base/models/ir_model.py b/odoo/addons/base/models/ir_model.py
index 17e953328fe..9a7f5864a9d 100644
--- a/odoo/addons/base/models/ir_model.py
+++ b/odoo/addons/base/models/ir_model.py
@@ -319,6 +319,11 @@ class IrModel(models.Model):
         # delete fields whose comodel is being removed
         self.env['ir.model.fields'].search([('relation', 'in', self.mapped('model'))]).unlink()
 
+        # delete ir_crons created by user
+        crons = self.env['ir.cron'].with_context(active_test=False).search([('model_id', 'in', self.ids)])
+        if crons:
+            crons.unlink()
+
         self._drop_table()
         res = super(IrModel, self).unlink()