diff --git a/composer.json b/composer.json
index 9185afbbd..e14f6301e 100644
--- a/composer.json
+++ b/composer.json
@@ -61,7 +61,7 @@
     },
     "extra": {
         "branch-alias": {
-            "4.x-dev": "4.4.x-dev"
+            "4.x-dev": "4.5.x-dev"
         },
         "expose": [
             "client/images",
diff --git a/src/ORM/DataList.php b/src/ORM/DataList.php
index 28f538e9f..9110caabb 100644
--- a/src/ORM/DataList.php
+++ b/src/ORM/DataList.php
@@ -771,6 +771,20 @@ class DataList extends ViewableData implements SS_List, Filterable, Sortable, Li
         return $this;
     }
 
+    /**
+     * Returns a generator for this DataList
+     *
+     * @return \Generator&DataObject[]
+     */
+    public function getGenerator()
+    {
+        $query = $this->dataQuery->query()->execute();
+
+        while ($row = $query->record()) {
+            yield $this->createDataObject($row);
+        }
+    }
+
     public function debug()
     {
         $val = "<h2>" . static::class . "</h2><ul>";
diff --git a/src/ORM/FieldType/DBForeignKey.php b/src/ORM/FieldType/DBForeignKey.php
index 1c4532204..d8afaab8c 100644
--- a/src/ORM/FieldType/DBForeignKey.php
+++ b/src/ORM/FieldType/DBForeignKey.php
@@ -87,12 +87,29 @@ class DBForeignKey extends DBInt
 
         // Add the count of the list to a cache for subsequent calls
         if (!isset(static::$foreignListCache[$hasOneClass])) {
+            // Let the DB do the threshold check as it will be faster - depending on the SQL engine it might only have
+            // to count indexes
+            $dataQuery = $list->dataQuery()->getFinalisedQuery();
+
+            // Clear order-by as it's not relevant for counts
+            $dataQuery->setOrderBy(false);
+            // Remove distinct. Applying distinct shouldn't be required provided relations are not applied.
+            $dataQuery->setDistinct(false);
+
+            $dataQuery->setSelect(['over_threshold' => 'count(*) > ' . (int) $threshold]);
+            $result = $dataQuery->execute()->column('over_threshold');
+
+            // Checking for 't' supports PostgreSQL before silverstripe/postgresql@2.2
+            $overThreshold = !empty($result) && ($result[0] === 't' ||  (int) $result[0] === 1);
+
             static::$foreignListCache[$hasOneClass] = [
-                'count' => $list->count(),
+                'overThreshold' => $overThreshold,
             ];
         }
 
-        if (static::$foreignListCache[$hasOneClass]['count'] < $threshold) {
+        $overThreshold = static::$foreignListCache[$hasOneClass]['overThreshold'];
+
+        if (!$overThreshold) {
             // Add the mapped list for the cache
             if (!isset(static::$foreignListCache[$hasOneClass]['map'])) {
                 static::$foreignListCache[$hasOneClass]['map'] = $list->map('ID', $titleField);