diff -r 2eee280a1354 -r 481259af4bdf mercurial/localrepo.py
--- a/mercurial/localrepo.py	Mon Mar 11 02:32:21 2019 +0100
+++ b/mercurial/localrepo.py	Mon Mar 11 02:34:12 2019 +0100
@@ -2095,6 +2095,10 @@
             for ctx in self['.'].parents():
                 ctx.manifest()  # accessing the manifest is enough
 
+            # accessing tags warm the cache
+            self.tags()
+            self.filtered('served').tags()
+
     def invalidatecaches(self):
 
         if r'_tagscache' in vars(self):