fix #937

Author: wojcikstefan

docs/guide/querying.rst

@@ -340,14 +340,19 @@ Javascript code that is executed on the database server.
 
 Counting results
 ----------------
-Just as with limiting and skipping results, there is a method on
-:class:`~mongoengine.queryset.QuerySet` objects --
-:meth:`~mongoengine.queryset.QuerySet.count`, but there is also a more Pythonic
-way of achieving this::
-
-    num_users = len(User.objects)
-
-Even if len() is the Pythonic way of counting results, keep in mind that if you concerned about performance, :meth:`~mongoengine.queryset.QuerySet.count` is the way to go since it only execute a server side count query, while len() retrieves the results, places them in cache, and finally counts them. If we compare the performance of the two operations, len() is much slower than :meth:`~mongoengine.queryset.QuerySet.count`.
+Just as with limiting and skipping results, there is a method on a
+:class:`~mongoengine.queryset.QuerySet` object --
+:meth:`~mongoengine.queryset.QuerySet.count`::
+
+    num_users = User.objects.count()
+
+You could technically use ``len(User.objects)`` to get the same result, but it
+would be significantly slower than :meth:`~mongoengine.queryset.QuerySet.count`.
+When you execute a server-side count query, you let MongoDB do the heavy
+lifting and you receive a single integer over the wire. Meanwhile, len()
+retrieves all the results, places them in a local cache, and finally counts
+them. If we compare the performance of the two operations, len() is much slower
+than :meth:`~mongoengine.queryset.QuerySet.count`.
 
 Further aggregation
 -------------------