diff --git a/include/poller.php b/include/poller.php
index bcdad586eb..934641c13c 100644
--- a/include/poller.php
+++ b/include/poller.php
@@ -237,7 +237,9 @@ function poller_execute($queue) {
 		$poller_last_update = time();
 
 		if ($age > 1) {
+			$stamp = (float)microtime(true);
 			dba::update('workerqueue', array('executed' => datetime_convert()), array('pid' => $mypid, 'done' => false));
+			$poller_db_duration += (microtime(true) - $stamp);
 		}
 
 		poller_exec_function($queue, $funcname, $argv);
@@ -468,46 +470,47 @@ function poller_max_connections_reached() {
  *
  */
 function poller_kill_stale_workers() {
-	$r = q("SELECT `pid`, `executed`, `priority`, `parameter` FROM `workerqueue` WHERE `executed` > '%s' AND NOT `done`", dbesc(NULL_DATE));
+	$entries = dba::p("SELECT `pid`, `executed`, `priority`, `parameter` FROM `workerqueue` WHERE `executed` > ? AND NOT `done` AND `pid` != 0", NULL_DATE);
 
-	if (!dbm::is_result($r)) {
-		// No processing here needed
-		return;
-	}
-
-	foreach ($r AS $pid) {
-		if (!posix_kill($pid["pid"], 0)) {
+	while ($entry = dba::fetch($entries)) {
+		if (!posix_kill($entry["pid"], 0)) {
 			dba::update('workerqueue', array('executed' => NULL_DATE, 'pid' => 0),
-					array('pid' => $pid["pid"], 'done' => false));
+					array('pid' => $entry["pid"], 'done' => false));
 		} else {
 			// Kill long running processes
-
 			// Check if the priority is in a valid range
-			if (!in_array($pid["priority"], array(PRIORITY_CRITICAL, PRIORITY_HIGH, PRIORITY_MEDIUM, PRIORITY_LOW, PRIORITY_NEGLIGIBLE))) {
-				$pid["priority"] = PRIORITY_MEDIUM;
+			if (!in_array($entry["priority"], array(PRIORITY_CRITICAL, PRIORITY_HIGH, PRIORITY_MEDIUM, PRIORITY_LOW, PRIORITY_NEGLIGIBLE))) {
+				$entry["priority"] = PRIORITY_MEDIUM;
 			}
 
 			// Define the maximum durations
-			$max_duration_defaults = array(PRIORITY_CRITICAL => 360, PRIORITY_HIGH => 10, PRIORITY_MEDIUM => 60, PRIORITY_LOW => 180, PRIORITY_NEGLIGIBLE => 360);
-			$max_duration = $max_duration_defaults[$pid["priority"]];
+			$max_duration_defaults = array(PRIORITY_CRITICAL => 720, PRIORITY_HIGH => 10, PRIORITY_MEDIUM => 60, PRIORITY_LOW => 180, PRIORITY_NEGLIGIBLE => 720);
+			$max_duration = $max_duration_defaults[$entry["priority"]];
 
-			$argv = json_decode($pid["parameter"]);
+			$argv = json_decode($entry["parameter"]);
 			$argv[0] = basename($argv[0]);
 
 			// How long is the process already running?
-			$duration = (time() - strtotime($pid["executed"])) / 60;
+			$duration = (time() - strtotime($entry["executed"])) / 60;
 			if ($duration > $max_duration) {
-				logger("Worker process ".$pid["pid"]." (".implode(" ", $argv).") took more than ".$max_duration." minutes. It will be killed now.");
-				posix_kill($pid["pid"], SIGTERM);
+				logger("Worker process ".$entry["pid"]." (".implode(" ", $argv).") took more than ".$max_duration." minutes. It will be killed now.");
+				posix_kill($entry["pid"], SIGTERM);
 
 				// We killed the stale process.
 				// To avoid a blocking situation we reschedule the process at the beginning of the queue.
-				// Additionally we are lowering the priority.
+				// Additionally we are lowering the priority. (But not PRIORITY_CRITICAL)
+				if ($entry["priority"] == PRIORITY_HIGH) {
+					$new_priority = PRIORITY_MEDIUM;
+				} elseif ($entry["priority"] == PRIORITY_MEDIUM) {
+					$new_priority = PRIORITY_LOW;
+				} elseif ($entry["priority"] != PRIORITY_CRITICAL) {
+					$new_priority = PRIORITY_NEGLIGIBLE;
+				}
 				dba::update('workerqueue',
-						array('executed' => NULL_DATE, 'created' => datetime_convert(), 'priority' => PRIORITY_NEGLIGIBLE, 'pid' => 0),
-						array('pid' => $pid["pid"], 'done' => false));
+						array('executed' => NULL_DATE, 'created' => datetime_convert(), 'priority' => $new_priority, 'pid' => 0),
+						array('pid' => $entry["pid"], 'done' => false));
 			} else {
-				logger("Worker process ".$pid["pid"]." (".implode(" ", $argv).") now runs for ".round($duration)." of ".$max_duration." allowed minutes. That's okay.", LOGGER_DEBUG);
+				logger("Worker process ".$entry["pid"]." (".implode(" ", $argv).") now runs for ".round($duration)." of ".$max_duration." allowed minutes. That's okay.", LOGGER_DEBUG);
 			}
 		}
 	}