diff --git a/openerp/fields.py b/openerp/fields.py
index a6775336a1e..b46e4e3cda7 100644
--- a/openerp/fields.py
+++ b/openerp/fields.py
@@ -30,6 +30,7 @@ import logging
 import pytz
 import xmlrpclib
 
+from openerp.sql_db import LazyCursor
 from openerp.tools import float_round, frozendict, html_sanitize, ustr, OrderedSet
 from openerp.tools import DEFAULT_SERVER_DATE_FORMAT as DATE_FORMAT
 from openerp.tools import DEFAULT_SERVER_DATETIME_FORMAT as DATETIME_FORMAT
@@ -1070,7 +1071,7 @@ class Float(Field):
     @property
     def digits(self):
         if callable(self._digits):
-            with fields._get_cursor() as cr:
+            with LazyCursor() as cr:
                 return self._digits(cr)
         else:
             return self._digits
@@ -1882,7 +1883,7 @@ class Id(Field):
         raise TypeError("field 'id' cannot be assigned")
 
 # imported here to avoid dependency cycle issues
-from openerp import SUPERUSER_ID, registry
+from openerp import SUPERUSER_ID
 from .exceptions import Warning, AccessError, MissingError
 from .models import BaseModel, MAGIC_COLUMNS
 from .osv import fields
diff --git a/openerp/osv/fields.py b/openerp/osv/fields.py
index 38b034dded1..54b39418b9c 100644
--- a/openerp/osv/fields.py
+++ b/openerp/osv/fields.py
@@ -43,21 +43,18 @@ import pytz
 import re
 import xmlrpclib
 from operator import itemgetter
-from contextlib import contextmanager
 from psycopg2 import Binary
 
 import openerp
 import openerp.tools as tools
+from openerp.sql_db import LazyCursor
 from openerp.tools.translate import _
 from openerp.tools import float_repr, float_round, frozendict, html_sanitize
 import simplejson
-from openerp import SUPERUSER_ID, registry
+from openerp import SUPERUSER_ID
 
-@contextmanager
-def _get_cursor():
-    # yield a valid cursor from any environment or create a new one if none found
-    with registry().cursor() as cr:
-        yield cr
+# deprecated; kept for backward compatibility only
+_get_cursor = LazyCursor
 
 EMPTY_DICT = frozendict()
 
@@ -396,7 +393,7 @@ class float(_column):
     @property
     def digits(self):
         if self._digits_compute:
-            with _get_cursor() as cr:
+            with LazyCursor() as cr:
                 return self._digits_compute(cr)
         else:
             return self._digits
@@ -1323,7 +1320,7 @@ class function(_column):
     @property
     def digits(self):
         if self._digits_compute:
-            with _get_cursor() as cr:
+            with LazyCursor() as cr:
                 return self._digits_compute(cr)
         else:
             return self._digits
diff --git a/openerp/sql_db.py b/openerp/sql_db.py
index f389a847548..a3af4be677a 100644
--- a/openerp/sql_db.py
+++ b/openerp/sql_db.py
@@ -443,6 +443,40 @@ class TestCursor(Cursor):
         self.execute("ROLLBACK TO SAVEPOINT test_cursor")
         self.execute("SAVEPOINT test_cursor")
 
+class LazyCursor(object):
+    """ A proxy object to a cursor. The cursor itself is allocated only if it is
+        needed. This class is useful for cached methods, that use the cursor
+        only in the case of a cache miss.
+    """
+    def __init__(self, dbname=None):
+        self._dbname = dbname
+        self._cursor = None
+        self._depth = 0
+
+    @property
+    def dbname(self):
+        return self._dbname or threading.currentThread().dbname
+
+    def __getattr__(self, name):
+        cr = self._cursor
+        if cr is None:
+            from openerp import registry
+            cr = self._cursor = registry(self.dbname).cursor()
+            for _ in xrange(self._depth):
+                cr.__enter__()
+        return getattr(cr, name)
+
+    def __enter__(self):
+        self._depth += 1
+        if self._cursor is not None:
+            self._cursor.__enter__()
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self._depth -= 1
+        if self._cursor is not None:
+            self._cursor.__exit__(exc_type, exc_value, traceback)
+
 class PsycoConnection(psycopg2.extensions.connection):
     pass