Running Django's own testsuite:
#./runtests.py --settings=test_sqlite --verbosity=0
and then alternating between trunk and patched version

Switched to branch 'master'
Ran 4218 tests in 590.286s

Switched to branch 'add_q_further'
Ran 4218 tests in 541.701s

Switched to branch 'master'
Ran 4218 tests in 583.265s

Switched to branch 'add_q_further'
Ran 4218 tests in 562.066s

Switched to branch 'master'
Ran 4218 tests in 644.779s

Switched to branch 'add_q_further'
Ran 4218 tests in 530.566s

Switched to branch 'master'
Ran 4218 tests in 592.954s

Switched to branch 'add_q_further'
Ran 4218 tests in 539.268s

Master Total: 2409
Where Refactor: 2172

Speedup about 10%

A couple of test with postgresql and the following model:

class User(models.Model):
    email = models.TextField()

The test file is as follows, you need to do some application setup:

import settings
from django.core.management import setup_environ
setup_environ(settings)

from test_models.models import User
from datetime import datetime
from django.db import transaction

User.objects.create(pk=1, email='foo@bar.com')

#Test 1
start = datetime.now()
for i in range(0, 1000):
    User.objects.filter(pk=1)
print datetime.now() - start

#Test 2
qs = User.objects.all()
start = datetime.now()
for i in range(0, 200):
    qs = qs.filter(pk=i)
print datetime.now() - start

# Test3
qs = User.objects.all()
@transaction.commit_on_success
def managed():
    start = datetime.now()
    for i in range(0, 1000):
        obj = User.objects.get(pk=1)
        obj.save() 
    print datetime.now() - start
managed()





