diff --git a/include/cron.php b/include/cron.php
index d95d8bc601..8bf168ed50 100644
--- a/include/cron.php
+++ b/include/cron.php
@@ -189,24 +189,39 @@ function cron_run(&$argv, &$argc){
 			q('DELETE FROM `photo` WHERE `uid` = 0 AND `resource-id` LIKE "pic:%%" AND `created` < NOW() - INTERVAL %d SECOND', $cachetime);
 		}
 
-		// maximum table size in megabyte
+		// Maximum table size in megabyte
 		$max_tablesize = intval(get_config('system','optimize_max_tablesize')) * 1000000;
 		if ($max_tablesize == 0)
 			$max_tablesize = 100 * 1000000; // Default are 100 MB
 
+		// Minimum fragmentation level in percent
+		$fragmentation_level = intval(get_config('system','optimize_fragmentation')) / 100;
+		if ($fragmentation_level == 0)
+			$fragmentation_level = 0.3; // Default value is 30%
+
 		// Optimize some tables that need to be optimized
 		$r = q("SHOW TABLE STATUS");
 		foreach($r as $table) {
 
-			// Don't optimize tables that needn't to be optimized
-			if ($table["Data_free"] == 0)
-				continue;
-
 			// Don't optimize tables that are too large
 			if ($table["Data_length"] > $max_tablesize)
 				continue;
 
+			// Don't optimize empty tables
+			if ($table["Data_length"] == 0)
+				continue;
+
+			// Calculate fragmentation
+			$fragmentation = $table["Data_free"] / $table["Data_length"];
+
+			logger("Table ".$table["Name"]." - Fragmentation level: ".round($fragmentation * 100, 2), LOGGER_DEBUG);
+
+			// Don't optimize tables that needn't to be optimized
+			if ($fragmentation < $fragmentation_level)
+				continue;
+
 			// So optimize it
+			logger("Optimize Table ".$table["Name"], LOGGER_DEBUG);
 			q("OPTIMIZE TABLE `%s`", dbesc($table["Name"]));
 		}
 
diff --git a/mod/admin.php b/mod/admin.php
index 8d2a7688f8..9e330fd1dc 100644
--- a/mod/admin.php
+++ b/mod/admin.php
@@ -410,6 +410,7 @@ function admin_page_site_post(&$a){
 	$maxloadavg		=	((x($_POST,'maxloadavg'))		? intval(trim($_POST['maxloadavg']))		: 50);
 	$maxloadavg_frontend	=	((x($_POST,'maxloadavg_frontend'))	? intval(trim($_POST['maxloadavg_frontend']))	: 50);
 	$optimize_max_tablesize	=	((x($_POST,'optimize_max_tablesize'))	? intval(trim($_POST['optimize_max_tablesize'])): 100);
+	$optimize_fragmentation	=	((x($_POST,'optimize_fragmentation'))	? intval(trim($_POST['optimize_fragmentation'])): 30);
 	$poco_completion	=	((x($_POST,'poco_completion'))		? intval(trim($_POST['poco_completion']))	: false);
 	$poco_requery_days	=	((x($_POST,'poco_requery_days'))	? intval(trim($_POST['poco_requery_days']))	: 7);
 	$poco_discovery		=	((x($_POST,'poco_discovery'))		? intval(trim($_POST['poco_discovery']))	: 0);
@@ -492,6 +493,7 @@ function admin_page_site_post(&$a){
 	set_config('system','maxloadavg',$maxloadavg);
 	set_config('system','maxloadavg_frontend',$maxloadavg_frontend);
 	set_config('system','optimize_max_tablesize',$optimize_max_tablesize);
+	set_config('system','optimize_fragmentation',$optimize_fragmentation);
 	set_config('system','poco_completion',$poco_completion);
 	set_config('system','poco_requery_days',$poco_requery_days);
 	set_config('system','poco_discovery',$poco_discovery);
@@ -775,6 +777,7 @@ function admin_page_site(&$a) {
 		'$maxloadavg'		=> array('maxloadavg', t("Maximum Load Average"), ((intval(get_config('system','maxloadavg')) > 0)?get_config('system','maxloadavg'):50), t("Maximum system load before delivery and poll processes are deferred - default 50.")),
 		'$maxloadavg_frontend'	=> array('maxloadavg_frontend', t("Maximum Load Average (Frontend)"), ((intval(get_config('system','maxloadavg_frontend')) > 0)?get_config('system','maxloadavg_frontend'):50), t("Maximum system load before the frontend quits service - default 50.")),
 		'$optimize_max_tablesize'=> array('optimize_max_tablesize', t("Maximum table size for optimization"), ((intval(get_config('system','optimize_max_tablesize')) > 0)?get_config('system','optimize_max_tablesize'):100), t("Maximum table size (in MB) for the automatic optimization - default 100 MB. Enter -1 to disable it.")),
+		'$optimize_fragmentation'=> array('optimize_fragmentation', t("Minimum level of fragmentation"), ((intval(get_config('system','optimize_fragmentation')) > 0)?get_config('system','optimize_fragmentation'):30), t("Minimum fragmenation level to start the automatic optimization - default value is 30%.")),
 
 		'$poco_completion'	=> array('poco_completion', t("Periodical check of global contacts"), get_config('system','poco_completion'), t("If enabled, the global contacts are checked periodically for missing or outdated data and the vitality of the contacts and servers.")),
 		'$poco_requery_days'	=> array('poco_requery_days', t("Days between requery"), get_config('system','poco_requery_days'), t("Number of days after which a server is requeried for his contacts.")),
diff --git a/view/templates/admin_site.tpl b/view/templates/admin_site.tpl
index c1e70614ce..b08e5f935f 100644
--- a/view/templates/admin_site.tpl
+++ b/view/templates/admin_site.tpl
@@ -124,6 +124,7 @@
 	{{include file="field_input.tpl" field=$maxloadavg}}
 	{{include file="field_input.tpl" field=$maxloadavg_frontend}}
 	{{include file="field_input.tpl" field=$optimize_max_tablesize}}
+	{{include file="field_input.tpl" field=$optimize_fragmentation}}
 	{{include file="field_input.tpl" field=$abandon_days}}
 	{{include file="field_input.tpl" field=$lockpath}}
 	{{include file="field_input.tpl" field=$temppath}}