diff -r 4d414ecf8416 -r d432911e3c26 cubicweb/pyramid/tools.py
--- a/cubicweb/pyramid/tools.py	Tue Feb 28 16:11:17 2017 +0100
+++ b/cubicweb/pyramid/tools.py	Tue Feb 28 16:46:16 2017 +0100
@@ -26,11 +26,7 @@
     with caution, as the API may change without notice.
 """
 
-#: A short-term cache for user clones.
-#: used by cached_build_user to speed-up repetitive calls to build_user
-#: The expiration is handled in a dumb and brutal way: the whole cache is
-#: cleared every 5 minutes.
-_user_cache = {}
+from repoze.lru import lru_cache
 
 
 def clone_user(repo, user):
@@ -59,34 +55,13 @@
         entity.cw_rset.req = cnx
 
 
+@lru_cache(10)
 def cached_build_user(repo, eid):
     """Cached version of
     :meth:`cubicweb.server.repository.Repository._build_user`
     """
-    if eid in _user_cache:
-        user, lang = _user_cache[eid]
-        entity = clone_user(repo, user)
-        return entity, lang
-
     with repo.internal_cnx() as cnx:
         user = repo._build_user(cnx, eid)
         lang = user.prefered_language()
         user.cw_clear_relation_cache()
-        _user_cache[eid] = (clone_user(repo, user), lang)
-        return user, lang
-
-
-def clear_cache():
-    """Clear the user cache"""
-    _user_cache.clear()
-
-
-def includeme(config):
-    """Start the cache maintenance loop task.
-
-    Automatically included by :mod:`cubicweb.pyramid`.
-    """
-    repo = config.registry['cubicweb.repository']
-    interval = int(config.registry.settings.get(
-        'cubicweb.usercache.expiration_time', 60 * 5))
-    repo.looping_task(interval, clear_cache)
+        return clone_user(repo, user), lang