diff -r 76b3cd5d4f31 -r 01152fffd593 server/sources/pyrorql.py
--- a/server/sources/pyrorql.py	Mon Apr 06 12:37:45 2009 +0200
+++ b/server/sources/pyrorql.py	Tue Apr 07 09:30:23 2009 +0200
@@ -22,7 +22,7 @@
 from cubicweb import dbapi, server
 from cubicweb import BadConnectionId, UnknownEid, ConnectionError
 from cubicweb.cwconfig import register_persistent_options
-from cubicweb.server.sources import AbstractSource, ConnectionWrapper
+from cubicweb.server.sources import AbstractSource, ConnectionWrapper, TimedCache
 
 class ReplaceByInOperator(Exception):
     def __init__(self, eids):
@@ -130,6 +130,7 @@
                        'group': 'sources', 
                        }),)
         register_persistent_options(myoptions)
+        self._query_cache = TimedCache(30)
 
     def last_update_time(self):
         pkey = u'sources.%s.latest-update-time' % self.uri
@@ -154,6 +155,7 @@
         """method called by the repository once ready to handle request"""
         interval = int(self.config.get('synchronization-interval', 5*60))
         self.repo.looping_task(interval, self.synchronize) 
+        self.repo.looping_task(self._query_cache.ttl.seconds/10, self._query_cache.clear_expired) 
 
     def synchronize(self, mtime=None):
         """synchronize content known by this repository with content in the
@@ -241,9 +243,18 @@
         # try to reconnect
         return self.get_connection()
         
-    
     def syntax_tree_search(self, session, union, args=None, cachekey=None,
                            varmap=None):
+        #assert not varmap, (varmap, union)
+        rqlkey = union.as_string(kwargs=args)
+        try:
+            results = self._query_cache[rqlkey]
+        except KeyError:
+            results = self._syntax_tree_search(session, union, args)
+            self._query_cache[rqlkey] = results
+        return results
+    
+    def _syntax_tree_search(self, session, union, args):
         """return result from this source for a rql query (actually from a rql 
         syntax tree and a solution dictionary mapping each used variable to a 
         possible type). If cachekey is given, the query necessary to fetch the