[IMP] website: don't query website table when serving homepage

We can easily avoid a read on the website table when serving the
homepage by simply caching the website.homepage_id value and then
browsing the record (no query needed) instead of reading it on the
website record.

While this code is not really elegant, it seems like a good tradeoff to
gain a query on this particular homepage serve controller, which is the
main entry point of a website and generally the page the more often
served.

task-2774979

X-original-commit: 69b443b85656c895c66a1f83b235f5d1e53727d4
Part-of: odoo/odoo#85456

addons/website/controllers/main.py

@@ -73,7 +73,8 @@ class Website(Home):
         # prefetch all menus (it will prefetch website.page too)
         top_menu = request.website.menu_id
 
-        homepage = request.website.homepage_id
+        homepage_id = request.website._get_cached('homepage_id')
+        homepage = homepage_id and request.env['website.page'].browse(homepage_id)
         if homepage and (homepage.sudo().is_visible or request.env.user.has_group('base.group_user')) and homepage.url != '/':
             return request.env['ir.http'].reroute(homepage.url)
 

addons/website/models/website.py

@@ -1350,6 +1350,7 @@ class Website(models.Model):
             'user_id': self.user_id.id,
             'company_id': self.company_id.id,
             'default_lang_id': self.default_lang_id.id,
+            'homepage_id': self.homepage_id.id,
         }
 
     def _get_cached(self, field):

addons/website/tests/test_performance.py

@@ -109,7 +109,7 @@ class TestWebsitePerformance(UtilPerf):
 
     def test_20_perf_sql_queries_homepage(self):
         # homepage "/" has its own controller
-        self.assertEqual(self._get_url_hot_query('/'), 13)
+        self.assertEqual(self._get_url_hot_query('/'), 12)
         self.assertEqual(self._get_url_hot_query('/', cache=False), 15)
 
     def test_30_perf_sql_queries_page_no_layout(self):