Set option "Optimize tables before backup" to default value "no" because some people experienced problems with big tables where this option leads to a timeout.

config.php

@@ -42,7 +42,7 @@ $config['compression']=1;
 $config['processlist_refresh']=3000;
 
 $config['empty_db_before_restore']=0;
-$config['optimize_tables_beforedump']=1;
+$config['optimize_tables_beforedump']=0;
 $config['stop_with_error']=1;
 
 // For sending a mail after backup set send_mail to 1, otherless set to 0