diff --git a/hc/accounts/backends.py b/hc/accounts/backends.py
index f18ca975..d21780b1 100644
--- a/hc/accounts/backends.py
+++ b/hc/accounts/backends.py
@@ -3,7 +3,7 @@ from django.contrib.auth.models import User
 from hc.accounts.models import Profile
 
 
-class BasicBackend:
+class BasicBackend(object):
 
     def get_user(self, user_id):
         try:
@@ -17,7 +17,8 @@ class ProfileBackend(BasicBackend):
 
     def authenticate(self, username=None, token=None):
         try:
-            profile = Profile.objects.get(user__username=username)
+            profile = (Profile.objects
+                       .select_related("user").get(user__username=username))
         except Profile.DoesNotExist:
             return None
 
@@ -27,10 +28,7 @@ class ProfileBackend(BasicBackend):
         return profile.user
 
     def get_user(self, user_id):
-        try:
-            return User.objects.get(pk=user_id)
-        except User.DoesNotExist:
-            return None
+        return User.objects.filter(pk=user_id).first()
 
 
 class EmailBackend(BasicBackend):
diff --git a/hc/api/management/commands/sendalerts.py b/hc/api/management/commands/sendalerts.py
index 333d1b3e..68666a8b 100644
--- a/hc/api/management/commands/sendalerts.py
+++ b/hc/api/management/commands/sendalerts.py
@@ -16,7 +16,7 @@ class Command(BaseCommand):
 
     def handle_many(self):
         """ Send alerts for many checks simultaneously. """
-        query = Check.objects.filter(user__isnull=False)
+        query = Check.objects.filter(user__isnull=False).select_related("user")
 
         now = timezone.now()
         going_down = query.filter(alert_after__lt=now, status="up")
diff --git a/hc/front/tests/test_add_channel.py b/hc/front/tests/test_add_channel.py
index 50b2a201..dd381e4e 100644
--- a/hc/front/tests/test_add_channel.py
+++ b/hc/front/tests/test_add_channel.py
@@ -7,6 +7,7 @@ from hc.api.models import Channel
 class AddChannelTestCase(TestCase):
 
     def setUp(self):
+        super(AddChannelTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_add_check.py b/hc/front/tests/test_add_check.py
index d4f6d06f..343a3bfb 100644
--- a/hc/front/tests/test_add_check.py
+++ b/hc/front/tests/test_add_check.py
@@ -6,6 +6,7 @@ from hc.api.models import Check
 class AddCheckTestCase(TestCase):
 
     def setUp(self):
+        super(AddCheckTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_channel_checks.py b/hc/front/tests/test_channel_checks.py
index 7ab2ac8f..05730d6e 100644
--- a/hc/front/tests/test_channel_checks.py
+++ b/hc/front/tests/test_channel_checks.py
@@ -6,6 +6,7 @@ from hc.api.models import Channel
 class ChannelChecksTestCase(TestCase):
 
     def setUp(self):
+        super(ChannelChecksTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_log.py b/hc/front/tests/test_log.py
index 0fb59933..49952762 100644
--- a/hc/front/tests/test_log.py
+++ b/hc/front/tests/test_log.py
@@ -6,6 +6,7 @@ from hc.api.models import Check, Ping
 class LogTestCase(TestCase):
 
     def setUp(self):
+        super(LogTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_my_checks.py b/hc/front/tests/test_my_checks.py
index 37a28f00..36a91f31 100644
--- a/hc/front/tests/test_my_checks.py
+++ b/hc/front/tests/test_my_checks.py
@@ -6,6 +6,7 @@ from hc.api.models import Check
 class MyChecksTestCase(TestCase):
 
     def setUp(self):
+        super(MyChecksTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_remove_channel.py b/hc/front/tests/test_remove_channel.py
index b1c25e41..22253d26 100644
--- a/hc/front/tests/test_remove_channel.py
+++ b/hc/front/tests/test_remove_channel.py
@@ -6,6 +6,7 @@ from hc.api.models import Channel
 class RemoveChannelTestCase(TestCase):
 
     def setUp(self):
+        super(RemoveChannelTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_remove_check.py b/hc/front/tests/test_remove_check.py
index 9f5cba3f..41d165c4 100644
--- a/hc/front/tests/test_remove_check.py
+++ b/hc/front/tests/test_remove_check.py
@@ -6,6 +6,7 @@ from hc.api.models import Check
 class RemoveCheckTestCase(TestCase):
 
     def setUp(self):
+        super(RemoveCheckTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_update_channel.py b/hc/front/tests/test_update_channel.py
index b3ecc205..3e35d90b 100644
--- a/hc/front/tests/test_update_channel.py
+++ b/hc/front/tests/test_update_channel.py
@@ -6,6 +6,7 @@ from hc.api.models import Channel, Check
 class UpdateChannelTestCase(TestCase):
 
     def setUp(self):
+        super(UpdateChannelTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_update_name.py b/hc/front/tests/test_update_name.py
index 520cc8a0..bbf37865 100644
--- a/hc/front/tests/test_update_name.py
+++ b/hc/front/tests/test_update_name.py
@@ -6,6 +6,7 @@ from hc.api.models import Check
 class UpdateNameTestCase(TestCase):
 
     def setUp(self):
+        super(UpdateNameTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_update_timeout.py b/hc/front/tests/test_update_timeout.py
index 1ee55ddc..0b06cdd8 100644
--- a/hc/front/tests/test_update_timeout.py
+++ b/hc/front/tests/test_update_timeout.py
@@ -6,6 +6,7 @@ from hc.api.models import Check
 class UpdateTimeoutTestCase(TestCase):
 
     def setUp(self):
+        super(UpdateTimeoutTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/tests/test_verify_email.py b/hc/front/tests/test_verify_email.py
index b38797ab..0bfb6069 100644
--- a/hc/front/tests/test_verify_email.py
+++ b/hc/front/tests/test_verify_email.py
@@ -6,6 +6,7 @@ from hc.api.models import Channel
 class VerifyEmailTestCase(TestCase):
 
     def setUp(self):
+        super(VerifyEmailTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/front/views.py b/hc/front/views.py
index 322868ee..44c3efa4 100644
--- a/hc/front/views.py
+++ b/hc/front/views.py
@@ -30,7 +30,7 @@ def my_checks(request):
 
     counter = Counter()
     down_tags, grace_tags = set(), set()
-    for check in checks:
+    for check in checks.iterator():
         status = check.get_status()
         for tag in check.tags_list():
             if tag == "":
@@ -196,7 +196,7 @@ def log(request, code):
     limit = profile.ping_log_limit
     pings = Ping.objects.filter(owner=check).order_by("-id")[:limit]
 
-    pings = list(pings)
+    pings = list(pings.iterator())
     # oldest-to-newest order will be more convenient for adding
     # "not received" placeholders:
     pings.reverse()
diff --git a/hc/payments/tests/test_billing.py b/hc/payments/tests/test_billing.py
index f2dcf43a..ce2aba13 100644
--- a/hc/payments/tests/test_billing.py
+++ b/hc/payments/tests/test_billing.py
@@ -7,6 +7,7 @@ from mock import Mock, patch
 class BillingTestCase(TestCase):
 
     def setUp(self):
+        super(BillingTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/payments/tests/test_cancel_plan.py b/hc/payments/tests/test_cancel_plan.py
index 40ba3fd0..adac22f8 100644
--- a/hc/payments/tests/test_cancel_plan.py
+++ b/hc/payments/tests/test_cancel_plan.py
@@ -7,6 +7,7 @@ from mock import patch
 class CancelPlanTestCase(TestCase):
 
     def setUp(self):
+        super(CancelPlanTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/payments/tests/test_create_plan.py b/hc/payments/tests/test_create_plan.py
index a476b167..1139fc1f 100644
--- a/hc/payments/tests/test_create_plan.py
+++ b/hc/payments/tests/test_create_plan.py
@@ -8,6 +8,7 @@ from mock import patch
 class CreatePlanTestCase(TestCase):
 
     def setUp(self):
+        super(CreatePlanTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/payments/tests/test_get_client_token.py b/hc/payments/tests/test_get_client_token.py
index 01ba3b62..d79aad1d 100644
--- a/hc/payments/tests/test_get_client_token.py
+++ b/hc/payments/tests/test_get_client_token.py
@@ -7,6 +7,7 @@ from mock import patch
 class GetClientTokenTestCase(TestCase):
 
     def setUp(self):
+        super(GetClientTokenTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/payments/tests/test_invoice.py b/hc/payments/tests/test_invoice.py
index 8ae735cd..c0737a49 100644
--- a/hc/payments/tests/test_invoice.py
+++ b/hc/payments/tests/test_invoice.py
@@ -7,6 +7,7 @@ from mock import Mock, patch
 class InvoiceTestCase(TestCase):
 
     def setUp(self):
+        super(InvoiceTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/hc/payments/tests/test_pricing.py b/hc/payments/tests/test_pricing.py
index 1ae04855..c617740e 100644
--- a/hc/payments/tests/test_pricing.py
+++ b/hc/payments/tests/test_pricing.py
@@ -6,6 +6,7 @@ from hc.payments.models import Subscription
 class PricingTestCase(TestCase):
 
     def setUp(self):
+        super(PricingTestCase, self).setUp()
         self.alice = User(username="alice", email="alice@example.org")
         self.alice.set_password("password")
         self.alice.save()
diff --git a/templates/front/channel_checks.html b/templates/front/channel_checks.html
index 005e8925..48127f2d 100644
--- a/templates/front/channel_checks.html
+++ b/templates/front/channel_checks.html
@@ -4,7 +4,7 @@
 {% csrf_token %}
 
 <div class="modal-header">
-    <button type="button" class="close" data-dismiss="modal">&times;</span></button>
+    <button type="button" class="close" data-dismiss="modal">&times;</button>
     <h4 class="update-timeout-title">Assign Checks to Channel {% if channel.kind == "po" %}{{ channel.po_value|join:" / " }}{% else %}{{ channel.value }}{% endif %}</h4>
 </div>
 
diff --git a/templates/front/channels.html b/templates/front/channels.html
index 59e3fb80..10f4bd25 100644
--- a/templates/front/channels.html
+++ b/templates/front/channels.html
@@ -149,8 +149,8 @@
             {% csrf_token %}
             <div class="modal-content">
                 <div class="modal-header">
-                    <button type="button" class="close" data-dismiss="modal">&times;</span></button>
-                    <h4 class="remove-check-title">Remove Channel <span class="remove-channel-name"></h4>
+                    <button type="button" class="close" data-dismiss="modal">&times;</button>
+                    <h4 class="remove-check-title">Remove Channel <span class="remove-channel-name"></span></h4>
                 </div>
                 <div class="modal-body">
                     <p>You are about to remove channel
@@ -177,4 +177,4 @@
 <script src="{% static 'js/bootstrap.min.js' %}"></script>
 <script src="{% static 'js/channels.js' %}"></script>
 {% endcompress %}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/templates/front/my_checks.html b/templates/front/my_checks.html
index a157cdf3..d3a63f66 100644
--- a/templates/front/my_checks.html
+++ b/templates/front/my_checks.html
@@ -52,7 +52,7 @@
             {% csrf_token %}
             <div class="modal-content">
                 <div class="modal-header">
-                    <button type="button" class="close" data-dismiss="modal">&times;</span></button>
+                    <button type="button" class="close" data-dismiss="modal">&times;</button>
                     <h4 class="update-timeout-title">Name and Tags</h4>
                 </div>
                 <div class="modal-body">
@@ -172,7 +172,7 @@
             <div class="modal-content">
                 <div class="modal-header">
                     <button type="button" class="close" data-dismiss="modal">&times;</span></button>
-                    <h4 class="remove-check-title">Remove Check <span class="remove-check-name"></h4>
+                    <h4 class="remove-check-title">Remove Check <span class="remove-check-name"></span></h4>
                 </div>
                 <div class="modal-body">
                     <p>You are about to remove check
diff --git a/templates/payments/pricing.html b/templates/payments/pricing.html
index 69e2c645..6921bcac 100644
--- a/templates/payments/pricing.html
+++ b/templates/payments/pricing.html
@@ -208,7 +208,7 @@
 
             <div class="modal-content">
                 <div class="modal-header">
-                    <button type="button" class="close" data-dismiss="modal">&times;</span></button>
+                    <button type="button" class="close" data-dismiss="modal">&times;</button>
                     <h4>Set Up Subscription</h4>
                 </div>
                 <div class="modal-body" id="payment-method-body">