diff --git a/addons/calendar/models/res_partner.py b/addons/calendar/models/res_partner.py
index 42137e79607..e1131c53566 100644
--- a/addons/calendar/models/res_partner.py
+++ b/addons/calendar/models/res_partner.py
@@ -1,7 +1,6 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from collections import defaultdict
 from datetime import datetime
 
 from odoo import api, fields, models
@@ -63,24 +62,20 @@ class Partner(models.Model):
         """
         attendees_details = []
         meetings = self.env['calendar.event'].browse(meeting_ids)
-        all_attendees = meetings.attendee_ids
-        attendees_by_partner = defaultdict(lambda: self.env['calendar.attendee'])
-        for attendee in all_attendees:
-            attendees_by_partner[attendee.partner_id.id] += attendee
-        for partner in self:
-            partner_info = partner.display_name
-            for attendee in attendees_by_partner[partner.id]:
-                attendee_is_organizer = self.env.user == attendee.event_id.user_id and attendee.partner_id == self.env.user.partner_id
-                attendees_details.append({
-                    'id': partner_info[0],
-                    'name': partner_info[1],
-                    'status': attendee.state,
-                    'event_id': attendee.event_id.id,
-                    'attendee_id': attendee.id,
-                    'is_alone': attendee.event_id.is_organizer_alone and attendee_is_organizer,
-                    # attendees data is sorted according to this key in JS.
-                    'is_organizer': 1 if attendee.partner_id == attendee.event_id.user_id.partner_id else 0,
-                })
+        for attendee in meetings.attendee_ids:
+            if attendee.partner_id not in self:
+                continue
+            attendee_is_organizer = self.env.user == attendee.event_id.user_id and attendee.partner_id == self.env.user.partner_id
+            attendees_details.append({
+                'id': attendee.partner_id.id,
+                'name': attendee.partner_id.display_name,
+                'status': attendee.state,
+                'event_id': attendee.event_id.id,
+                'attendee_id': attendee.id,
+                'is_alone': attendee.event_id.is_organizer_alone and attendee_is_organizer,
+                # attendees data is sorted according to this key in JS.
+                'is_organizer': 1 if attendee.partner_id == attendee.event_id.user_id.partner_id else 0,
+            })
         return attendees_details
 
     @api.model