diff --git a/addons/im_livechat/tests/__init__.py b/addons/im_livechat/tests/__init__.py
index 370f87695ea..b2509c74792 100644
--- a/addons/im_livechat/tests/__init__.py
+++ b/addons/im_livechat/tests/__init__.py
@@ -9,6 +9,5 @@ from . import test_get_discuss_channel
 from . import test_get_random_operator
 from . import test_im_livechat_report
 from . import test_im_livechat_support_page
-from . import test_performance
 from . import test_js
 from . import test_message
diff --git a/addons/im_livechat/tests/test_performance.py b/addons/im_livechat/tests/test_performance.py
deleted file mode 100644
index 59e79e1e41d..00000000000
--- a/addons/im_livechat/tests/test_performance.py
+++ /dev/null
@@ -1,20 +0,0 @@
-from odoo.addons.test_discuss_full.tests.test_performance import TestDiscussFullPerformance
-
-old_method = TestDiscussFullPerformance._get_init_messaging_result
-
-
-def _get_init_messaging_result(self):
-    res = old_method(self)
-    for channel in res['channels']:
-        if not channel['channel']['channel_type'] == 'livechat':
-            continue
-        for channel_member in channel['channel']['channelMembers'][0][1]:
-            channel_member['persona']['partner']['is_bot'] = False
-    return res
-
-def _get_query_count(self):
-    return 79
-
-
-TestDiscussFullPerformance._get_init_messaging_result = _get_init_messaging_result
-TestDiscussFullPerformance._get_query_count = _get_query_count
diff --git a/addons/mail/models/discuss/discuss_channel.py b/addons/mail/models/discuss/discuss_channel.py
index 6aa3de13fda..42546df2ccf 100644
--- a/addons/mail/models/discuss/discuss_channel.py
+++ b/addons/mail/models/discuss/discuss_channel.py
@@ -758,13 +758,27 @@ class Channel(models.Model):
         rtc_sessions_by_channel = self.sudo().rtc_session_ids._mail_rtc_session_format_by_channel()
         channel_last_message_ids = dict((r['id'], r['message_id']) for r in self._channel_last_message_ids())
         current_partner, current_guest = self.env["res.partner"]._get_current_persona()
-        all_needed_members_domain = expression.OR([
-            [('channel_id.channel_type', '!=', 'channel')],
-            [('rtc_inviting_session_id', '!=', False)],
-            [('partner_id', '=', current_partner.id) if current_partner else expression.FALSE_LEAF],
-            [('guest_id', '=', current_guest.id) if current_guest else expression.FALSE_LEAF],
-        ])
-        all_needed_members = self.env['discuss.channel.member'].search(expression.AND([[('channel_id', 'in', self.ids)], all_needed_members_domain]), order='id')
+        self.env['discuss.channel'].flush_model()
+        self.env['discuss.channel.member'].flush_model()
+        # Query instead of ORM for performance reasons: "LEFT JOIN" is more
+        # efficient than "id IN" for the cross-table condition between channel
+        # (for channel_type) and member (for other fields).
+        self.env.cr.execute("""
+                 SELECT discuss_channel_member.id
+                   FROM discuss_channel_member
+              LEFT JOIN discuss_channel
+                     ON discuss_channel.id = discuss_channel_member.channel_id
+                    AND discuss_channel.channel_type != 'channel'
+                  WHERE discuss_channel_member.channel_id in %(channel_ids)s
+                    AND (
+                        discuss_channel.id IS NOT NULL
+                     OR discuss_channel_member.rtc_inviting_session_id IS NOT NULL
+                     OR discuss_channel_member.partner_id = %(current_partner_id)s
+                     OR discuss_channel_member.guest_id = %(current_guest_id)s
+                    )
+               ORDER BY discuss_channel_member.id ASC
+        """, {'channel_ids': tuple(self.ids), 'current_partner_id': current_partner.id or None, 'current_guest_id': current_guest.id or None})
+        all_needed_members = self.env['discuss.channel.member'].browse([m['id'] for m in self.env.cr.dictfetchall()])
         all_needed_members.partner_id.sudo().mail_partner_format()  # prefetch in batch
         members_by_channel = defaultdict(lambda: self.env['discuss.channel.member'])
         invited_members_by_channel = defaultdict(lambda: self.env['discuss.channel.member'])
diff --git a/addons/test_discuss_full/tests/test_performance.py b/addons/test_discuss_full/tests/test_performance.py
index 251c615d0d0..0c691a9f844 100644
--- a/addons/test_discuss_full/tests/test_performance.py
+++ b/addons/test_discuss_full/tests/test_performance.py
@@ -816,6 +816,7 @@ class TestDiscussFullPerformance(TransactionCase):
                                         'active': True,
                                         'country': [('clear',)],
                                         'id': self.users[0].partner_id.id,
+                                        'is_bot': False,
                                         'is_public': False,
                                         'name': 'Ernest Employee',
                                     },
@@ -831,6 +832,7 @@ class TestDiscussFullPerformance(TransactionCase):
                                         'active': True,
                                         'country': [('clear',)],
                                         'id': self.users[1].partner_id.id,
+                                        'is_bot': False,
                                         'is_public': False,
                                         'name': 'test1',
                                     },
@@ -897,6 +899,7 @@ class TestDiscussFullPerformance(TransactionCase):
                                         'active': True,
                                         'country': [('clear',)],
                                         'id': self.users[0].partner_id.id,
+                                        'is_bot': False,
                                         'is_public': False,
                                         'name': 'Ernest Employee',
                                     },
@@ -911,6 +914,7 @@ class TestDiscussFullPerformance(TransactionCase):
                                     'partner': {
                                         'active': False,
                                         'id': self.env.ref('base.public_partner').id,
+                                        'is_bot': False,
                                         'is_public': True,
                                         'name': 'Public user',
                                     },
@@ -1012,4 +1016,4 @@ class TestDiscussFullPerformance(TransactionCase):
             Returns the expected query count.
             The point of having a separate getter is to allow it to be overriden.
         """
-        return 75
+        return 66