diff --git a/config/dbstructure.config.php b/config/dbstructure.config.php
index 050543675a..6ce9d69474 100644
--- a/config/dbstructure.config.php
+++ b/config/dbstructure.config.php
@@ -34,7 +34,7 @@
 use Friendica\Database\DBA;
 
 if (!defined('DB_UPDATE_VERSION')) {
-	define('DB_UPDATE_VERSION', 1303);
+	define('DB_UPDATE_VERSION', 1302);
 }
 
 return [
@@ -1378,8 +1378,9 @@ return [
 			"PRIMARY" => ["id"],
 			"done_parameter" => ["done", "parameter(64)"],
 			"done_executed" => ["done", "executed"],
+			"done_priority" => ["done", "priority"],
 			"done_priority_created" => ["done", "priority", "created"],
-			"done_priority_next_try" => ["done", "priority", "next_try"],
+			"done_pid" => ["done", "pid"],
 			"done_pid_next_try" => ["done", "pid", "next_try"],
 			"done_pid_priority_created" => ["done", "pid", "priority", "created"]
 		]
diff --git a/mod/worker.php b/mod/worker.php
index 23dfd6e000..1afbfe81c1 100644
--- a/mod/worker.php
+++ b/mod/worker.php
@@ -41,7 +41,11 @@ function worker_init()
 
 	Worker::callWorker();
 
-	if ($r = Worker::workerProcess()) {
+	$passing_slow = false;
+	$entries = 0;
+	$deferred = 0;
+
+	if ($r = Worker::workerProcess($passing_slow, $entries, $deferred)) {
 		// On most configurations this parameter wouldn't have any effect.
 		// But since it doesn't destroy anything, we just try to get more execution time in any way.
 		set_time_limit(0);
diff --git a/src/Core/Worker.php b/src/Core/Worker.php
index 3f55aede33..4007a7923c 100644
--- a/src/Core/Worker.php
+++ b/src/Core/Worker.php
@@ -92,8 +92,15 @@ class Worker
 
 		$starttime = time();
 
+		$entries = 0;
+		$deferred = 0;
+
 		// We fetch the next queue entry that is about to be executed
-		while ($r = self::workerProcess()) {
+		while ($r = self::workerProcess($passing_slow, $entries, $deferred)) {
+			// When we are processing jobs with a lower priority, we don't refetch new jobs
+			// Otherwise fast jobs could wait behind slow ones and could be blocked.
+			$refetched = $passing_slow;
+
 			foreach ($r as $entry) {
 				// Assure that the priority is an integer value
 				$entry['priority'] = (int)$entry['priority'];
@@ -105,16 +112,20 @@ class Worker
 				}
 
 				// If possible we will fetch new jobs for this worker
-				if (!self::getWaitingJobForPID() && Lock::acquire('worker_process', 0)) {
-					self::findWorkerProcesses();
-					Lock::release('worker_process');
+				if (!$refetched) {
+					$entries = self::totalEntries();
+					$deferred = self::deferredEntries();
+					if (Lock::acquire('worker_process', 0)) {
+						$refetched = self::findWorkerProcesses($passing_slow, $entries, $deferred);
+						Lock::release('worker_process');
+					}
 				}
 			}
 
 			// To avoid the quitting of multiple workers only one worker at a time will execute the check
 			if (Lock::acquire('worker', 0)) {
 				// Count active workers and compare them with a maximum value that depends on the load
-				if (self::tooMuchWorkers()) {
+				if (self::tooMuchWorkers($entries, $deferred)) {
 					Logger::log('Active worker limit reached, quitting.', Logger::DEBUG);
 					Lock::release('worker');
 					return;
@@ -398,15 +409,16 @@ class Worker
 		 * The execution time is the productive time.
 		 * By changing parameters like the maximum number of workers we can check the effectivness.
 		*/
-		$dbtotal = number_format(self::$db_duration - (self::$db_duration_count + self::$db_duration_write + self::$db_duration_stat), 4);
-		$dbcount = number_format(self::$db_duration_count, 4);
-		$dbstat  = number_format(self::$db_duration_stat, 4);
-		$dbwrite = number_format(self::$db_duration_write, 4);
-		$dblock  = number_format(self::$lock_duration, 4);
-		$rest    = number_format(max(0, $up_duration - (self::$db_duration + self::$lock_duration)), 4);
-		$exec    = number_format($duration, 4);
-
-		Logger::info('Performance:', ['total' => $dbtotal, 'count' => $dbcount, 'stat' => $dbstat, 'write' => $dbwrite, 'block' => $dblock, 'rest' => $rest, 'exec' => $exec]);
+		Logger::log(
+			'DB: '.number_format(self::$db_duration - (self::$db_duration_count + self::$db_duration_write + self::$db_duration_stat), 4).
+			' - DB-Count: '.number_format(self::$db_duration_count, 4).
+			' - DB-Stat: '.number_format(self::$db_duration_stat, 4).
+			' - DB-Write: '.number_format(self::$db_duration_write, 4).
+			' - Lock: '.number_format(self::$lock_duration, 4).
+			' - Rest: '.number_format(max(0, $up_duration - (self::$db_duration + self::$lock_duration)), 4).
+			' - Execution: '.number_format($duration, 4),
+			Logger::DEBUG
+		);
 
 		self::$up_start = microtime(true);
 		self::$db_duration = 0;
@@ -595,10 +607,13 @@ class Worker
 	/**
 	 * @brief Checks if the number of active workers exceeds the given limits
 	 *
+	 * @param integer $entries Total number of queue entries
+	 * @param integer $deferred Number of deferred queue entries
+	 *
 	 * @return bool Are there too much workers running?
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 */
-	private static function tooMuchWorkers()
+	public static function tooMuchWorkers($entries = 0, $deferred = 0)
 	{
 		$queues = Config::get("system", "worker_queues", 4);
 
@@ -649,7 +664,12 @@ class Worker
 
 			$idle_workers = $active;
 
-			$deferred = self::deferredEntries();
+			if (empty($deferred) && empty($entries)) {
+				$deferred = self::deferredEntries();
+				$entries = max(self::totalEntries() - $deferred, 0);
+			}
+
+			$waiting_processes = max(0, $entries - $deferred);
 
 			if (Config::get('system', 'worker_debug')) {
 				$waiting_processes = 0;
@@ -671,14 +691,10 @@ class Worker
 					DBA::close($processes);
 				}
 				DBA::close($jobs);
-				$entries = $deferred + $waiting_processes;
 			} else {
-				$entries = self::totalEntries();
-				$waiting_processes = max(0, $entries - $deferred);
 				$stamp = (float)microtime(true);
 				$jobs = DBA::p("SELECT COUNT(*) AS `running`, `priority` FROM `process` INNER JOIN `workerqueue` ON `workerqueue`.`pid` = `process`.`pid` AND NOT `done` GROUP BY `priority` ORDER BY `priority`");
 				self::$db_duration += (microtime(true) - $stamp);
-				self::$db_duration_stat += (microtime(true) - $stamp);
 
 				while ($entry = DBA::fetch($jobs)) {
 					$idle_workers -= $entry["running"];
@@ -737,13 +753,201 @@ class Worker
 	}
 
 	/**
-	 * @brief Returns waiting jobs for the current process id
+	 * @brief Check if we should pass some slow processes
 	 *
-	 * @return array waiting workerqueue jobs
+	 * When the active processes of the highest priority are using more than 2/3
+	 * of all processes, we let pass slower processes.
+	 *
+	 * @param string $highest_priority Returns the currently highest priority
+	 * @return bool We let pass a slower process than $highest_priority
 	 * @throws \Exception
 	 */
-	private static function getWaitingJobForPID()
+	private static function passingSlow(&$highest_priority)
 	{
+		$highest_priority = 0;
+
+		$stamp = (float)microtime(true);
+		$r = DBA::p(
+			"SELECT `priority`
+				FROM `process`
+				INNER JOIN `workerqueue` ON `workerqueue`.`pid` = `process`.`pid` AND NOT `done`"
+		);
+		self::$db_duration += (microtime(true) - $stamp);
+
+		// No active processes at all? Fine
+		if (!DBA::isResult($r)) {
+			return false;
+		}
+		$priorities = [];
+		while ($line = DBA::fetch($r)) {
+			$priorities[] = $line["priority"];
+		}
+		DBA::close($r);
+
+		// Should not happen
+		if (count($priorities) == 0) {
+			return false;
+		}
+		$highest_priority = min($priorities);
+
+		// The highest process is already the slowest one?
+		// Then we quit
+		if ($highest_priority == PRIORITY_NEGLIGIBLE) {
+			return false;
+		}
+		$high = 0;
+		foreach ($priorities as $priority) {
+			if ($priority == $highest_priority) {
+				++$high;
+			}
+		}
+		Logger::log("Highest priority: ".$highest_priority." Total processes: ".count($priorities)." Count high priority processes: ".$high, Logger::DEBUG);
+		$passing_slow = (($high/count($priorities)) > (2/3));
+
+		if ($passing_slow) {
+			Logger::log("Passing slower processes than priority ".$highest_priority, Logger::DEBUG);
+		}
+		return $passing_slow;
+	}
+
+	/**
+	 * @brief Find and claim the next worker process for us
+	 *
+	 * @param boolean $passing_slow Returns if we had passed low priority processes
+	 * @param integer $entries Total number of queue entries
+	 * @param integer $deferred Number of deferred queue entries
+	 * @return boolean Have we found something?
+	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 */
+	private static function findWorkerProcesses(&$passing_slow, $entries, $deferred)
+	{
+		$mypid = getmypid();
+
+		// Check if we should pass some low priority process
+		$highest_priority = 0;
+		$found = false;
+		$passing_slow = false;
+
+		// The higher the number of parallel workers, the more we prefetch to prevent concurring access
+		// We decrease the limit with the number of entries left in the queue
+		$worker_queues = Config::get("system", "worker_queues", 4);
+		$queue_length = Config::get('system', 'worker_fetch_limit', 1);
+		$lower_job_limit = $worker_queues * $queue_length * 2;
+		$entries = max($entries - $deferred, 0);
+
+		// Now do some magic
+		$exponent = 2;
+		$slope = $queue_length / pow($lower_job_limit, $exponent);
+		$limit = min($queue_length, ceil($slope * pow($entries, $exponent)));
+
+		Logger::log('Deferred: ' . $deferred . ' - Total: ' . $entries . ' - Maximum: ' . $queue_length . ' - jobs per queue: ' . $limit, Logger::DEBUG);
+		$ids = [];
+		if (self::passingSlow($highest_priority)) {
+			// Are there waiting processes with a higher priority than the currently highest?
+			$stamp = (float)microtime(true);
+			$result = DBA::select(
+				'workerqueue',
+				['id'],
+				["`pid` = 0 AND `priority` < ? AND NOT `done` AND `next_try` < ?",
+				$highest_priority, DateTimeFormat::utcNow()],
+				['limit' => 1, 'order' => ['priority', 'created']]
+			);
+			self::$db_duration += (microtime(true) - $stamp);
+
+			while ($id = DBA::fetch($result)) {
+				$ids[] = $id["id"];
+			}
+			DBA::close($result);
+
+			$found = (count($ids) > 0);
+
+			if (!$found) {
+				// Give slower processes some processing time
+				$stamp = (float)microtime(true);
+				$result = DBA::select(
+					'workerqueue',
+					['id'],
+					["`pid` = 0 AND `priority` > ? AND NOT `done` AND `next_try` < ?",
+					$highest_priority, DateTimeFormat::utcNow()],
+					['limit' => 1, 'order' => ['priority', 'created']]
+				);
+				self::$db_duration += (microtime(true) - $stamp);
+
+				while ($id = DBA::fetch($result)) {
+					$ids[] = $id["id"];
+				}
+				DBA::close($result);
+
+				$found = (count($ids) > 0);
+				$passing_slow = $found;
+			}
+		}
+
+		// At first try to fetch a bunch of high or medium tasks
+		if (!$found && ($limit > 1)) {
+			$stamp = (float)microtime(true);
+			$result = DBA::select(
+				'workerqueue',
+				['id'],
+				["`pid` = 0 AND NOT `done` AND `priority` <= ? AND `next_try` < ? AND `retrial` = 0",
+				PRIORITY_MEDIUM, DateTimeFormat::utcNow()],
+				['limit' => $limit, 'order' => ['created']]
+			);
+			self::$db_duration += (microtime(true) - $stamp);
+
+			while ($id = DBA::fetch($result)) {
+				$ids[] = $id["id"];
+			}
+			DBA::close($result);
+
+			$found = (count($ids) > 0);
+		}
+
+		// If there is no result (or we shouldn't pass lower processes) we check without priority limit
+		if (!$found) {
+			$stamp = (float)microtime(true);
+			$result = DBA::select(
+				'workerqueue',
+				['id'],
+				["`pid` = 0 AND NOT `done` AND `next_try` < ?",
+				DateTimeFormat::utcNow()],
+				['limit' => 1, 'order' => ['priority', 'created']]
+			);
+			self::$db_duration += (microtime(true) - $stamp);
+
+			while ($id = DBA::fetch($result)) {
+				$ids[] = $id["id"];
+			}
+			DBA::close($result);
+
+			$found = (count($ids) > 0);
+		}
+
+		if ($found) {
+			$stamp = (float)microtime(true);
+			$condition = "`id` IN (".substr(str_repeat("?, ", count($ids)), 0, -2).") AND `pid` = 0 AND NOT `done`";
+			array_unshift($ids, $condition);
+			DBA::update('workerqueue', ['executed' => DateTimeFormat::utcNow(), 'pid' => $mypid], $ids);
+			self::$db_duration += (microtime(true) - $stamp);
+			self::$db_duration_write += (microtime(true) - $stamp);
+		}
+
+		return $found;
+	}
+
+	/**
+	 * @brief Returns the next worker process
+	 *
+	 * @param boolean $passing_slow Returns if we had passed low priority processes
+	 * @param integer $entries Returns total number of queue entries
+	 * @param integer $deferred Returns number of deferred queue entries
+	 *
+	 * @return string SQL statement
+	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 */
+	public static function workerProcess(&$passing_slow, &$entries, &$deferred)
+	{
+		// There can already be jobs for us in the queue.
 		$stamp = (float)microtime(true);
 		$r = DBA::select('workerqueue', [], ['pid' => getmypid(), 'done' => false]);
 		self::$db_duration += (microtime(true) - $stamp);
@@ -752,165 +956,9 @@ class Worker
 		}
 		DBA::close($r);
 
-		return false;
-	}
-
-	/**
-	 * @brief Returns the next jobs that should be executed
-	 *
-	 * @return array array with next jobs
-	 * @throws \Exception
-	 */
-	private static function nextProcess()
-	{
-		$priority = self::nextPriority();
-		if (empty($priority)) {
-			Logger::info('No tasks found');
-			return [];
-		}
-
-		if ($priority <= PRIORITY_MEDIUM) {
-			$limit = Config::get('system', 'worker_fetch_limit', 1);
-		} else {
-			$limit = 1;
-		}
-
-		$ids = [];
-		$stamp = (float)microtime(true);
-		$condition = ["`priority` = ? AND `pid` = 0 AND NOT `done` AND `next_try` < ?", $priority, DateTimeFormat::utcNow()];
-		$tasks = DBA::select('workerqueue', ['id'], $condition, ['limit' => $limit, 'order' => ['created']]);
-		self::$db_duration += (microtime(true) - $stamp);
-		while ($task = DBA::fetch($tasks)) {
-			$ids[] = $task['id'];
-		}
-		DBA::close($tasks);
-
-		Logger::info('Found:', ['id' => $ids, 'priority' => $priority]);
-		return $ids;
-	}
-
-	/**
-	 * @brief Returns the priority of the next workerqueue job
-	 *
-	 * @return string priority
-	 * @throws \Exception
-	 */
-	private static function nextPriority()
-	{
-		$waiting = [];
-		$priorities = [PRIORITY_CRITICAL, PRIORITY_HIGH, PRIORITY_MEDIUM, PRIORITY_LOW, PRIORITY_NEGLIGIBLE];
-		foreach ($priorities as $priority) {
-			$stamp = (float)microtime(true);
-			if (DBA::exists('workerqueue', ["`priority` = ? AND `pid` = 0 AND NOT `done` AND `next_try` < ?", $priority, DateTimeFormat::utcNow()])) {
-				$waiting[$priority] = true;
-			}
-			self::$db_duration += (microtime(true) - $stamp);
-		}
-
-		if (!empty($waiting[PRIORITY_CRITICAL])) {
-			return PRIORITY_CRITICAL;
-		}
-
-		$running = [];
-		$running_total = 0;
-		$stamp = (float)microtime(true);
-		$processes = DBA::p("SELECT COUNT(DISTINCT(`process`.`pid`)) AS `running`, `priority` FROM `process`
-			INNER JOIN `workerqueue` ON `workerqueue`.`pid` = `process`.`pid`
-			WHERE NOT `done` GROUP BY `priority`");
-		self::$db_duration += (microtime(true) - $stamp);
-		while ($process = DBA::fetch($processes)) {
-			$running[$process['priority']] = $process['running'];
-			$running_total += $process['running'];
-		}
-		DBA::close($processes);
-
-		foreach ($priorities as $priority) {
-			if (!empty($waiting[$priority]) && empty($running[$priority])) {
-				Logger::info('No running worker found with priority {priority} - assigning it.', ['priority' => $priority]);
-				return $priority;
-			}
-		}
-
-		$active = max(self::activeWorkers(), $running_total);
-		$priorities = max(count($waiting), count($running));
-		$exponent = 2;
-
-		$total = 0;
-		for ($i = 1; $i <= $priorities; ++$i) {
-			$total += pow($i, $exponent);
-		}
-
-		$limit = [];
-		for ($i = 1; $i <= $priorities; ++$i) {
-			$limit[$priorities - $i] = max(1, round($active * (pow($i, $exponent) / $total)));
-		}
-
-		$i = 0;
-		foreach ($running as $priority => $workers) {
-			if ($workers < $limit[$i++]) {
-				Logger::info('Priority {priority} has got {workers} workers out of a limit of {limit}', ['priority' => $priority, 'workers' => $workers, 'limit' => $limit[$i - 1]]);
-				return $priority;
-			}
-		}
-
-		if (!empty($waiting)) {
-			$priority =  array_shift(array_keys($waiting));
-			Logger::info('No underassigned priority found, now taking the highest priority.', ['priority' => $priority]);
-			return $priority;
-		}
-
-		return false;
-	}
-
-	/**
-	 * @brief Find and claim the next worker process for us
-	 *
-	 * @return boolean Have we found something?
-	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
-	 */
-	private static function findWorkerProcesses()
-	{
-		$mypid = getmypid();
-
-		$ids = self::nextProcess();
-
-		// If there is no result we check without priority limit
-		if (empty($ids)) {
-			$stamp = (float)microtime(true);
-			$condition = ["`pid` = 0 AND NOT `done` AND `next_try` < ?", DateTimeFormat::utcNow()];
-			$result = DBA::select('workerqueue', ['id'], $condition, ['limit' => 1, 'order' => ['priority', 'created']]);
-			self::$db_duration += (microtime(true) - $stamp);
-
-			while ($id = DBA::fetch($result)) {
-				$ids[] = $id["id"];
-			}
-			DBA::close($result);
-		}
-
-		if (!empty($ids)) {
-			$stamp = (float)microtime(true);
-			$condition = ['id' => $ids, 'done' => false, 'pid' => 0];
-			DBA::update('workerqueue', ['executed' => DateTimeFormat::utcNow(), 'pid' => $mypid], $condition);
-			self::$db_duration += (microtime(true) - $stamp);
-			self::$db_duration_write += (microtime(true) - $stamp);
-		}
-
-		return !empty($ids);
-	}
-
-	/**
-	 * @brief Returns the next worker process
-	 *
-	 * @return string SQL statement
-	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
-	 */
-	public static function workerProcess()
-	{
-		// There can already be jobs for us in the queue.
-		$waiting = self::getWaitingJobForPID();
-		if (!empty($waiting)) {
-			return $waiting;
-		}
+		// Counting the rows outside the lock reduces the lock time
+		$entries = self::totalEntries();
+		$deferred = self::deferredEntries();
 
 		$stamp = (float)microtime(true);
 		if (!Lock::acquire('worker_process')) {
@@ -918,7 +966,7 @@ class Worker
 		}
 		self::$lock_duration += (microtime(true) - $stamp);
 
-		$found = self::findWorkerProcesses();
+		$found = self::findWorkerProcesses($passing_slow, $entries, $deferred);
 
 		Lock::release('worker_process');
 
diff --git a/src/Model/Contact.php b/src/Model/Contact.php
index d38d1cc101..2d6bc716bb 100644
--- a/src/Model/Contact.php
+++ b/src/Model/Contact.php
@@ -616,7 +616,7 @@ class Contact extends BaseObject
 		DBA::update('contact', ['archive' => true, 'network' => Protocol::PHANTOM, 'deleted' => true], ['id' => $id]);
 
 		// Delete it in the background
-		Worker::add(PRIORITY_MEDIUM, 'RemoveContact', $id);
+		Worker::add(PRIORITY_LOW, 'RemoveContact', $id);
 	}
 
 	/**