diff --git a/htdocs/main.inc.php b/htdocs/main.inc.php
index c8c2b4576c6..69dd0062a32 100644
--- a/htdocs/main.inc.php
+++ b/htdocs/main.inc.php
@@ -759,7 +759,7 @@ function top_htmlhead($head, $title='', $disablejs=0, $disablehead=0, $arrayofjs
 			require_once DOL_DOCUMENT_ROOT.'/lib/ajax.lib.php';
 
 			$mini='';$ext='.js';
-			if (! empty($conf->global->MAIN_OPTIMIZE_SPEED)) { $mini='_mini'; $ext='.jgz'; }	// mini='_mini', ext='.gz'
+			if (isset($conf->global->MAIN_OPTIMIZE_SPEED) && ($conf->global->MAIN_OPTIMIZE_SPEED & 0x01)) { $mini='_mini'; $ext='.jgz'; }	// mini='_mini', ext='.gz'
 
 			// This one is required for all Ajax features
 			if (! defined('DISABLE_PROTOTYPE'))
@@ -1174,7 +1174,7 @@ function llxFooter($foot='')
 	if (! empty($_SERVER['DOL_TUNING']))
 	{
 		$micro_end_time=dol_microtime_float(true);
-		print "\n".'<script type="text/javascript">window.status="MAIN_OPTIMIZE_SPEED '.(empty($conf->global->MAIN_OPTIMIZE_SPEED)?'off - ':'on - ').'Build time: '.ceil(1000*($micro_end_time-$micro_start_time)).' ms';
+		print "\n".'<script type="text/javascript">window.status="MAIN_OPTIMIZE_SPEED '.(isset($conf->global->MAIN_OPTIMIZE_SPEED)?$conf->global->MAIN_OPTIMIZE_SPEED:'off').' - Build time: '.ceil(1000*($micro_end_time-$micro_start_time)).' ms';
 		if (function_exists("memory_get_usage"))
 		{
 			print ' - Mem: '.memory_get_usage();
diff --git a/htdocs/translate.class.php b/htdocs/translate.class.php
index 1dd1f322c42..7a92a3706cd 100644
--- a/htdocs/translate.class.php
+++ b/htdocs/translate.class.php
@@ -197,7 +197,7 @@ class Translate {
 
 				// Enable cache of lang file in memory (faster but need more memory)
 				// Speed gain: 40ms - Memory overusage: 200ko (Size of session cache file)
-				$enablelangcacheinmemory=empty($conf->global->MAIN_OPTIMIZE_SPEED)?0:$conf->global->MAIN_OPTIMIZE_SPEED;
+				$enablelangcacheinmemory=((isset($conf->global->MAIN_OPTIMIZE_SPEED) && ($conf->global->MAIN_OPTIMIZE_SPEED & 0x02))?true:false);
 				//$enablelangcacheinmemory=true;
 
 				if ($alt == 2 && $enablelangcacheinmemory)