diff --git a/lib/BackgroundJob/Tasks/CreateClustersTask.php b/lib/BackgroundJob/Tasks/CreateClustersTask.php
index e173701c..67f2064d 100644
--- a/lib/BackgroundJob/Tasks/CreateClustersTask.php
+++ b/lib/BackgroundJob/Tasks/CreateClustersTask.php
@@ -148,13 +148,11 @@ private function createClusterIfNeeded(string $userId) {
 		$min_face_size = $this->settingsService->getMinimumFaceSize();
 		$min_confidence = $this->settingsService->getMinimumConfidence();
 
-		$faces = array_merge(
-			$this->faceMapper->getGroupableFaces($userId, $modelId, $min_face_size, $min_confidence),
-			$this->faceMapper->getNonGroupableFaces($userId, $modelId, $min_face_size, $min_confidence)
-		);
+		$faces = $this->faceMapper->getGroupableFaces($userId, $modelId, $min_face_size, $min_confidence);
+		$nonGroupables = $this->faceMapper->getNonGroupableFaces($userId, $modelId, $min_face_size, $min_confidence);
 
 		$facesCount = count($faces);
-		$this->logInfo('There are ' . $facesCount . ' faces for clustering');
+		$this->logInfo('There are ' . $facesCount . ' faces for clustering and '. count($nonGroupables) . ' that cannot be grouped.');
 
 		$noSlices = 1;
 		$sliceSize = $facesCount;
@@ -169,19 +167,30 @@ private function createClusterIfNeeded(string $userId) {
 			$sliceSize = ceil($facesCount / $noSlices);
 		}
 
-		$this->logDebug('We will cluster with ' . $noSlices . ' batch(es) of ' . $sliceSize . ' faces');
+		$this->logDebug('We will cluster these with ' . $noSlices . ' batch(es) of ' . $sliceSize . ' faces.');
 
 		$newClusters = [];
+		// Obtain the clusters in batches and append them.
 		for ($i = 0; $i < $noSlices ; $i++) {
+			// Get the batches.
 			$facesSliced = array_slice($faces, $i * $sliceSize, $sliceSize);
-			$newClusters = array_merge($newClusters, $this->getNewClusters($facesSliced));
+			// Get the indices, obtain the partial clusters and incorporate them.
+			$faceIds = array_map(function ($face) { return $face['id']; }, $facesSliced);
+			$facesDescripted = $this->faceMapper->findDescriptorsBathed($faceIds);
+			$newClusters = array_merge($newClusters, $this->getNewClusters($facesDescripted));
+			// Discard variables aggressively to improve memory consumption.
+			unset($facesDescripted);
+			unset($facesSliced);
 		}
 
+		// Append non groupable faces on a single step.
+		$newClusters = array_merge($newClusters, $this->getFakeClusters($nonGroupables));
+
 		// Cluster is associative array where key is person ID.
 		// Value is array of face IDs. For old clusters, person IDs are some existing person IDs,
 		// and for new clusters is whatever chinese whispers decides to identify them.
 		//
-		$currentClusters = $this->getCurrentClusters($faces);
+		$currentClusters = $this->getCurrentClusters(array_merge($faces, $nonGroupables));
 
 		$this->logInfo(count($newClusters) . ' clusters found after clustering');
 
@@ -279,16 +288,26 @@ private function needCreateFirstTime(string $userId, int $modelId): bool {
 	private function getCurrentClusters(array $faces): array {
 		$chineseClusters = array();
 		foreach($faces as $face) {
-			if ($face->person !== null) {
-				if (!isset($chineseClusters[$face->person])) {
-					$chineseClusters[$face->person] = array();
+			if ($face['person'] !== null) {
+				if (!isset($chineseClusters[$face['person']])) {
+					$chineseClusters[$face['person']] = array();
 				}
-				$chineseClusters[$face->person][] = $face->id;
+				$chineseClusters[$face['person']][] = $face['id'];
 			}
 		}
 		return $chineseClusters;
 	}
 
+	private function getFakeClusters(array $faces): array {
+		$newClusters = array();
+		for ($i = 0, $c = count($faces); $i < $c; $i++) {
+			$fakeCluster = [];
+			$fakeCluster[] = $faces[$i]['id'];
+			$newClusters[] = $fakeCluster;
+		}
+		return $newClusters;
+	}
+
 	private function getNewClusters(array $faces): array {
 		// Clustering parameters
 		$sensitivity = $this->settingsService->getSensitivity();
@@ -299,16 +318,9 @@ private function getNewClusters(array $faces): array {
 			$faces_count = count($faces);
 			for ($i = 0; $i < $faces_count; $i++) {
 				$face1 = $faces[$i];
-				if (!isset($face1->descriptor)) {
-					$edges[] = array($i, $i);
-					continue;
-				}
 				for ($j = $i; $j < $faces_count; $j++) {
 					$face2 = $faces[$j];
-					if (!isset($face2->descriptor)) {
-						continue;
-					}
-					$distance = dlib_vector_length($face1->descriptor, $face2->descriptor);
+					$distance = dlib_vector_length($face1['descriptor'], $face2['descriptor']);
 					if ($distance < $sensitivity) {
 						$edges[] = array($i, $j);
 					}
@@ -324,16 +336,9 @@ private function getNewClusters(array $faces): array {
 
 			for ($i = 0; $i < $faces_count; $i++) {
 				$face1 = $faces[$i];
-				if (!isset($face1->descriptor)) {
-					$edges[] = array($i, $i);
-					continue;
-				}
 				for ($j = $i; $j < $faces_count; $j++) {
 					$face2 = $faces[$j];
-					if (!isset($face2->descriptor)) {
-						continue;
-					}
-					$distance = Euclidean::distance($face1->descriptor, $face2->descriptor);
+					$distance = Euclidean::distance($face1['descriptor'], $face2['descriptor']);
 					if ($distance < $sensitivity) {
 						$edges[] = array($i, $j);
 					}
@@ -358,7 +363,7 @@ private function getNewClusters(array $faces): array {
 			if (!isset($newClusters[$newChineseClustersByIndex[$i]])) {
 				$newClusters[$newChineseClustersByIndex[$i]] = array();
 			}
-			$newClusters[$newChineseClustersByIndex[$i]][] = $faces[$i]->id;
+			$newClusters[$newChineseClustersByIndex[$i]][] = $faces[$i]['id'];
 		}
 		return $newClusters;
 	}
diff --git a/lib/Db/FaceMapper.php b/lib/Db/FaceMapper.php
index 0e31ea8c..74ecbd29 100644
--- a/lib/Db/FaceMapper.php
+++ b/lib/Db/FaceMapper.php
@@ -41,7 +41,7 @@ public function find (int $faceId): ?Face {
 		$qb = $this->db->getQueryBuilder();
 		$qb->select('id', 'image', 'person', 'x', 'y', 'width', 'height', 'landmarks', 'descriptor', 'confidence')
 			->from($this->getTableName(), 'f')
-			->andWhere($qb->expr()->eq('id', $qb->createNamedParameter($faceId)));
+			->where($qb->expr()->eq('id', $qb->createNamedParameter($faceId)));
 		try {
 			return $this->findEntity($qb);
 		} catch (DoesNotExistException $e) {
@@ -49,6 +49,27 @@ public function find (int $faceId): ?Face {
 		}
 	}
 
+	public function findDescriptorsBathed (array $faceIds): array {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('id', 'descriptor')
+			->from($this->getTableName(), 'f')
+			->where($qb->expr()->in('id', $qb->createParameter('face_ids')));
+
+		$qb->setParameter('face_ids', $faceIds, IQueryBuilder::PARAM_INT_ARRAY);
+
+		$descriptors = [];
+		$result = $qb->executeQuery();
+		while ($row = $result->fetch()) {
+			$descriptors[] = [
+				'id' => $row['id'],
+				'descriptor' => json_decode($row['descriptor'])
+			];
+		}
+		$result->closeCursor();
+
+		return $descriptors;
+	}
+
 	/**
 	 * Based on a given fileId, takes all faces that belong to that file
 	 * and return an array with that.
@@ -147,7 +168,7 @@ public function getFaces(string $userId, int $model): array {
 
 	public function getGroupableFaces(string $userId, int $model, int $minSize, float $minConfidence): array {
 		$qb = $this->db->getQueryBuilder();
-		$qb->select('f.id', 'f.person', 'f.descriptor')
+		$qb->select('f.id', 'f.person')
 			->from($this->getTableName(), 'f')
 			->innerJoin('f', 'facerecog_images' ,'i', $qb->expr()->eq('f.image', 'i.id'))
 			->where($qb->expr()->eq('user', $qb->createParameter('user')))
@@ -161,7 +182,12 @@ public function getGroupableFaces(string $userId, int $model, int $minSize, floa
 			->setParameter('min_size', $minSize)
 			->setParameter('min_confidence', $minConfidence)
 			->setParameter('is_groupable', true, IQueryBuilder::PARAM_BOOL);
-		return $this->findEntities($qb);
+
+		$result = $qb->executeQuery();
+		$rows = $result->fetchAll();
+		$result->closeCursor();
+
+		return $rows;
 	}
 
 	public function getNonGroupableFaces(string $userId, int $model, int $minSize, float $minConfidence): array {
@@ -182,7 +208,12 @@ public function getNonGroupableFaces(string $userId, int $model, int $minSize, f
 			->setParameter('min_size', $minSize)
 			->setParameter('min_confidence', $minConfidence)
 			->setParameter('is_groupable', false, IQueryBuilder::PARAM_BOOL);
-		return $this->findEntities($qb);
+
+		$result = $qb->executeQuery();
+		$rows = $result->fetchAll();
+		$result->closeCursor();
+
+		return $rows;
 	}
 
 	/**