diff --git a/judge/views/contests.py b/judge/views/contests.py
index 51e9297..0e71646 100644
--- a/judge/views/contests.py
+++ b/judge/views/contests.py
@@ -1018,7 +1018,7 @@ def base_contest_ranking_list(contest, problems, queryset, show_final=False):
 
 
 def contest_ranking_list(contest, problems, queryset=None, show_final=False):
-    if not queryset:
+    if queryset is None:
         queryset = contest.users.filter(virtual=0)
 
     if not show_final:
diff --git a/templates/blog/content.html b/templates/blog/content.html
index ac89ca4..8171d28 100644
--- a/templates/blog/content.html
+++ b/templates/blog/content.html
@@ -5,7 +5,7 @@
         {% with authors=post.get_authors() %}
           {%- if authors -%}
             <span class="user-img" style="width: 1.5em; height: 1.5em">
-              <img src="{{gravatar(authors[0])}}">
+              <img src="{{gravatar(authors[0])}}" loading="lazy">
             </span>
             <span class="post-authors">{{ link_users(authors) }}</span>
           {%- endif -%}
diff --git a/templates/chat/message.html b/templates/chat/message.html
index 7068af1..a253fab 100644
--- a/templates/chat/message.html
+++ b/templates/chat/message.html
@@ -1,6 +1,6 @@
 <li class="message" id="message-{{ message.id }}" message-id="{{ message.id }}">
   <a href="{{ url('user_page', message.author.username) }}">
-    <img src="{{ gravatar(message.author, 135) }}" class="profile-pic user-img">
+    <img loading="lazy" src="{{ gravatar(message.author, 135) }}" class="profile-pic user-img">
   </a>
   <div class="body-message">
     <div class="user-time">
diff --git a/templates/chat/online_status.html b/templates/chat/online_status.html
index 754137c..d17b6ff 100644
--- a/templates/chat/online_status.html
+++ b/templates/chat/online_status.html
@@ -1,6 +1,6 @@
 <li class="status-row" id="lobby_row">
   <div class="status-container">
-    <img src="{{ static('icons/icon.svg') }}" style="height:32px">
+    <img loading="lazy" src="{{ static('icons/icon.svg') }}" style="height:32px">
   </div>
   <span style="padding-left:0.5em">
     <b>{{_('Lobby')}}</b>
@@ -23,7 +23,7 @@
       {% for user in section.user_list %}
         <li class="click_space status-row" id="click_space_{{user.user.id}}" value="{{user.url}}">
           <div class="status-container">
-            <img src="{{ gravatar(user.user, 135) }}" class="status-pic user-img">
+            <img loading="lazy" src="{{ gravatar(user.user, 135) }}" class="status-pic user-img">
             <svg style="position:absolute;" height="32" width="32">
               <circle class="status-circle" fill="{{'green' if user.is_online else 'red'}}"/>
             </svg>
diff --git a/templates/course/list.html b/templates/course/list.html
index 2d43db2..90b86b9 100644
--- a/templates/course/list.html
+++ b/templates/course/list.html
@@ -14,7 +14,7 @@
     {% for course in courses %}
       <div class="course-item">
         <div class="course-image">
-          <img src="{{course.image_url}}">
+          <img loading="lazy" src="{{course.image_url}}">
         </div>
         <div class="course-content">
           <a href="{{url('course_detail', course.slug)}}" class="course-name">{{course.name}}</a>
diff --git a/templates/submission/row.html b/templates/submission/row.html
index 2adf4fc..94ccd6a 100644
--- a/templates/submission/row.html
+++ b/templates/submission/row.html
@@ -1,6 +1,6 @@
 {% set can_view = submission.is_accessible_by(profile) %}
 <div class="sub-user-img user-img">
-  <img src="{{gravatar(submission.user)}}">
+  <img loading="lazy" src="{{gravatar(submission.user)}}">
 </div>
 <div class="sub-details">
   <div class="sub-info{% if submission.status == 'G' %} sub-info-grading{% endif %}">
diff --git a/templates/ticket/message.html b/templates/ticket/message.html
index f6084ae..cf3a0cf 100644
--- a/templates/ticket/message.html
+++ b/templates/ticket/message.html
@@ -4,7 +4,7 @@
     <div class="header">
       <div class="info">
         <a class="user-container" href="{{ url('user_page', message.user.user.username) }}" class="user">
-          <img src="{{ gravatar(message.user, 135) }}" class="gravatar">
+          <img loading="lazy" src="{{ gravatar(message.user, 135) }}" class="gravatar">
           <span class="username {{ message.user.css_class }}">{{ message.user.user.username }}</span>
         </a>
       </div>
diff --git a/templates/ticket/ticket.html b/templates/ticket/ticket.html
index e1462ce..2693455 100644
--- a/templates/ticket/ticket.html
+++ b/templates/ticket/ticket.html
@@ -162,7 +162,7 @@
       <section class="message new-message">
         <div class="info">
           <a href="{{ url('user_page', request.user.username) }}" class="user">
-            <img src="{{ gravatar(request.profile, 135) }}" class="gravatar">
+            <img loading="lazy" src="{{ gravatar(request.profile, 135) }}" class="gravatar">
             <div class="username {{ request.profile.css_class }}">{{ request.user.username }}</div>
           </a>
         </div>
diff --git a/templates/user/link.html b/templates/user/link.html
index 49d158f..473dc6f 100644
--- a/templates/user/link.html
+++ b/templates/user/link.html
@@ -1,7 +1,7 @@
 <span class="{{ profile.css_class }} {{'user-with-img' if show_image}}">
   {% if show_image %}
     <span class="user-img">
-      <img src="{{gravatar(profile)}}">
+      <img loading="lazy" src="{{gravatar(profile)}}">
     </span>
   {% endif %}
   <a href="{{ url('user_page', profile.username) }}">
diff --git a/templates/user/users-table.html b/templates/user/users-table.html
index dfdcbe2..4424007 100644
--- a/templates/user/users-table.html
+++ b/templates/user/users-table.html
@@ -5,7 +5,7 @@
 {% endblock %}
 
 {% block after_rank %}
-  <td><img style="border: 2px solid lightblue; max-width: none;" class="user-img" src="{{ gravatar(user, 45) }}" height="45px" width="45px"></td>
+  <td><img loading="lazy" style="border: 2px solid lightblue; max-width: none;" class="user-img" src="{{ gravatar(user, 45) }}" height="45px" width="45px"></td>
 {% endblock %}
 
 {% block user_footer %}