[IMP] http_routing: use cached code from lang

In case of short controller that don't use qweb template, we don't need
anyhting else that this url code that don't change frequently.

It make only sense for model like lang, website, ... that will not change
frequently. And are called on each call by the dispatcher.

In case of a website page, we will btw browse lang later, but in case of
small controller like /favicon.ico, or page without qweb, ... we can just
use the same from last query.

addons/http_routing/models/ir_http.py

@@ -411,7 +411,7 @@ class IrHttp(models.AbstractModel):
                 lang = preferred_lang or cls._get_default_lang()
 
             request.lang = lang
-            context['lang'] = lang.code
+            context['lang'] = lang._get_cached('code')
 
             # bind modified context
             request.context = context

addons/website/tests/test_performance.py

@@ -95,7 +95,7 @@ class TestWebsitePerformance(UtilPerf):
     def test_30_perf_sql_queries_page_no_layout(self):
         # website.page with no call to layout templates
         self.page.arch = '<div>I am a blank page</div>'
-        self.assertEqual(self._get_url_hot_query(self.page.url), 10)
+        self.assertEqual(self._get_url_hot_query(self.page.url), 9)
 
     def test_40_perf_sql_queries_page_multi_level_menu(self):
         # menu structure should not impact SQL requests

odoo/addons/base/models/res_lang.py

@@ -213,6 +213,19 @@ class Lang(models.Model):
         langs = self.with_context(active_test=False).search([])
         return sorted([(lang.code, lang.url_code, lang.name) for lang in langs], key=itemgetter(2))
 
+    @tools.ormcache('self.id')
+    def _get_cached_values(self):
+        self.ensure_one()
+        return {
+            'id': self.id,
+            'code': self.code,
+            'url_code': self.url_code,
+            'name': self.name,
+        }
+
+    def _get_cached(self, field):
+        return self._get_cached_values()[field]
+
     @api.model
     @tools.ormcache('code')
     def _lang_code_to_urlcode(self, code):