diff --git a/devel_node_access.js b/devel_node_access.js
new file mode 100644
index 0000000..60f782c
--- /dev/null
+++ b/devel_node_access.js
@@ -0,0 +1,64 @@
+/**
+ * @file devel_node_access.js.
+ */
+
+(function ($) {
+
+  /**
+   * Perform the access by user ajax request.
+   */
+  function devel_node_access_user_ajax(context) {
+    // Get the cell ID for the first .dna-permission that isn't processed.
+    var cell = $('td.dna-permission', context)
+               .not('.ajax-processed', context)
+               .attr('id');
+    if (cell !== undefined) {
+      // Generate the URI from the basePath, path, data type, cell ID, and a
+      // random token to bypass caching.
+      var url = Drupal.settings.basePath
+              + "?q="
+              + 'devel/node_access/by_user/json/'
+              + cell
+              + '/'
+              + Math.floor((1000000000 * Math.random())).toString(16);
+      // Execute Ajax callback and handle the response.
+      $.getJSON(url, function(data) {
+        $('#' + cell, context).html(data).addClass('ajax-processed');
+        // Call this function again.
+        devel_node_access_user_ajax(context);
+      });
+      // Ajax fails silently on error, mark bad requests with an error message.
+      // If the request is just slow this will update when the request succeeds.
+      setTimeout(
+        function() {
+          if ($('#' + cell, context).hasClass('ajax-processed') == false) {
+            $('#' + cell, context)
+              .html(
+                '<span class="error">'
+                + '<a href="' + url.replace('/json/', '/html/') + '">'
+                + Drupal.t('Error: could not explain access')
+                + '</a>'
+                + '</span>'
+              )
+              .addClass('ajax-processed');
+            // Call this function again.
+            devel_node_access_user_ajax(context);
+          }
+        },
+        3000
+      );
+
+    }
+  }
+
+  /**
+   * Attach the access by user behavior which initiates ajax.
+   */
+  Drupal.behaviors.develNodeAccessUserAjax = {
+    attach: function(context) {
+      // Start the ajax.
+      devel_node_access_user_ajax(context);
+    }
+  };
+
+})(jQuery);
\ No newline at end of file
diff --git a/devel_node_access.module b/devel_node_access.module
index 758af15..2154cca 100644
--- a/devel_node_access.module
+++ b/devel_node_access.module
@@ -21,7 +21,7 @@ function devel_node_access_permission() {
 }
 
 /**
- * Implementation of hook_help().
+ * Implements of hook_help().
  */
 function devel_node_access_help($path, $arg) {
   switch ($path) {
@@ -68,6 +68,16 @@ function devel_node_access_menu() {
     $items['devel/settings'] = $items['admin/config/development/devel'] + array(
       'menu_name' => 'devel',
     );
+
+    // create a callback for use by devel_node_access_user_ajax().
+    $items['devel/node_access/by_user/%/%'] = array(
+      'title'            => 'Devel node access user ajax',
+      'page callback'    => 'devel_node_access_user_ajax',
+      'page arguments'   => array(3, 4),
+      'access arguments' => array(DNA_ACCESS_VIEW),
+      'type'             => MENU_CALLBACK,
+    );
+
   }
 
   // add this to the custom menu 'devel' created by the devel module.
@@ -104,6 +114,12 @@ function devel_node_access_form_alter(&$form, $form_state, $form_id) {
         '@link' => url('admin/structure/block/list'),
       )),
     );
+    $form['devel_node_access']['devel_node_access_user_ajax'] = array(
+      '#type'          => 'checkbox',
+      '#title'         => t('Asynchronously populate the <em>Devel Node Access by User</em> block'),
+      '#default_value' => variable_get('devel_node_access_user_ajax', FALSE),
+      '#description'   => t("Use Ajax to populate the second DNA block. This loads the initial page faster and uses dynamic calls to build the data in the table, one request at a time. It's especially useful during development, if some of the calls are failing.") . '<br />' . t('JavaScript must be enabled in your browser.'),
+    );
     // push the Save button down
     $form['actions']['#weight'] = 10;
   }
@@ -957,6 +973,10 @@ function devel_node_access_block_view($delta) {
         $node_type = node_type_get_type($node);
         $headers = array(t('username'), '<span title="' . t("Create nodes of the '@Node_type' type.", array('@Node_type' => $node_type->name)) . '">' . t('create') . '</span>', t('view'), t('update'), t('delete'));
         $rows = array();
+        // Determine whether to use Ajax or prepopulate the tables.
+        if ($ajax = variable_get('devel_node_access_user_ajax', FALSE)) {
+          drupal_add_js(drupal_get_path('module', 'devel_node_access') . '/devel_node_access.js');
+        }
         // Find all users. The following operations are very inefficient, so we
         // limit the number of users returned.  It would be better to make a
         // pager query, or at least make the number of users configurable.  If
@@ -975,10 +995,26 @@ function devel_node_access_block_view($delta) {
           }
           $rows[] = array(
             $username,
-            theme('dna_permission', _devel_node_access_explain_access('create', $nid, $account)),
-            theme('dna_permission', _devel_node_access_explain_access('view', $nid, $account)),
-            theme('dna_permission', _devel_node_access_explain_access('update', $nid, $account)),
-            theme('dna_permission', _devel_node_access_explain_access('delete', $nid, $account)),
+            array(
+              'id' => 'create-' . $nid . '-' . $account->uid,
+              'class' => 'dna-permission',
+              'data' => $ajax ? NULL : theme('dna_permission', array('permission' => _devel_node_access_explain_access('create', $nid, $account))),
+            ),
+            array(
+              'id' => 'view-' . $nid . '-' . $account->uid,
+              'class' => 'dna-permission',
+              'data' => $ajax ? NULL : theme('dna_permission', array('permission' => _devel_node_access_explain_access('view', $nid, $account))),
+            ),
+            array(
+              'id' => 'update-' . $nid . '-' . $account->uid,
+              'class' => 'dna-permission',
+              'data' => $ajax ? NULL : theme('dna_permission', array('permission' => _devel_node_access_explain_access('update', $nid, $account))),
+            ),
+            array(
+              'id' => 'delete-' . $nid . '-' . $account->uid,
+              'class' => 'dna-permission',
+              'data' => $ajax ? NULL : theme('dna_permission', array('permission' => _devel_node_access_explain_access('delete', $nid, $account))),
+            ),
           );
         }
         if (count($rows)) {
@@ -1004,6 +1040,42 @@ function devel_node_access_block_view($delta) {
 }
 
 /**
+ * Callback function for node access by user block ajax.
+ */
+function devel_node_access_user_ajax($data_type, $cell) {
+  list($op, $nid, $uid) = explode('-', $cell);
+  $account = user_load($uid);
+  $output = array(
+    '#theme' => 'dna_permission',
+    '#permission' => _devel_node_access_explain_access($op, $nid, $account),
+  );
+  // JSON output for Ajax callbacks.
+  if ($data_type == 'json') {
+    drupal_json_output(drupal_render($output));
+    exit;
+  }
+  // HTML output for error message click-throughs.
+  if ($node = node_load($nid)) {
+    $node_title = l($node->title, 'node/' . $node->nid);
+  }
+  else {
+    $node_title = t('unknown node %nid', array('%nid' => $nid));
+  }
+  drupal_set_title(
+    t(
+      'Devel node access: %op permission for !user on !node',
+      array(
+        '%op'   => $op,
+        '!user' => theme('username', array('account' => $account)),
+        '!node' => $node_title,
+      )
+    ),
+    PASS_THROUGH
+  );
+  return $output;
+}
+
+/**
  * Helper function that mimicks node.module's node_access() function.
  *
  * Unfortunately, this needs to be updated manually whenever node.module changes!
@@ -1261,12 +1333,14 @@ function _devel_node_access_format_row($row, $may_unpack = TRUE) {
 }
 
 /**
- * Implementation of hook_theme().
+ * Implements of hook_theme().
  */
 function devel_node_access_theme() {
   return array(
     'dna_permission' => array(
-      'arguments'    => array('permission' => NULL),
+      'variables'    => array(
+        'permission' => NULL,
+      ),
     ),
   );
 }
@@ -1274,6 +1348,7 @@ function devel_node_access_theme() {
 /**
  * Indicate whether user has a permission or not.
  */
-function theme_dna_permission($permission) {
+function theme_dna_permission($variables) {
+  $permission = &$variables['permission'];
   return '<span class="' . ($permission[0] ? 'ok' : 'error') . '" title="' . $permission[2] . '">' . $permission[1] . '</span>';
 }