diff --git a/config.php-dist b/config.php-dist
index 72320bc5f..6561ecbd4 100644
--- a/config.php-dist
+++ b/config.php-dist
@@ -163,27 +163,6 @@
 	// These two options enable SMTP authentication when sending
 	// outgoing mail. Only used with SMTP_HOST
 
-	// **************************************
-	// *** Update proces tuning settings  ***
-	// **************************************
-
-	define('FEED_FETCH_TIMEOUT', 45);
-	// How may seconds to wait for response when requesting feed from a site
-	// You may need to decease this if you see errors like "MySQL server
-	// has gone away" pop up in your feed update logs after fetching feeds
-	// from slow websites
-
-	define('FEED_FETCH_NO_CACHE_TIMEOUT', 15);
-	// How may seconds to wait for response when requesting feed from a
-	// site when that feed wasn't cached before
-
-	define('FILE_FETCH_TIMEOUT', 45);
-	// Default timeout when fetching files from remote sites
-
-	define('FILE_FETCH_CONNECT_TIMEOUT', 15);
-	// How many seconds to wait for initial response from website when
-	// fetching files from remote sites
-
 	// ***************************************
 	// *** Other settings (less important) ***
 	// ***************************************
diff --git a/include/functions.php b/include/functions.php
index e2a2282d5..039048095 100644
--- a/include/functions.php
+++ b/include/functions.php
@@ -30,6 +30,27 @@
 
 	require_once 'config.php';
 
+	/**
+	 * Define a constant if not already defined
+	 *
+	 * @param string $name The constant name.
+	 * @param mixed $value The constant value.
+	 * @access public
+	 * @return boolean True if defined successfully or not.
+	 */
+	function define_default($name, $value) {
+		// Note: performence freaks should define everything in 
+		// tunables.php in config.php becasue if will make defined() 
+		// run much faster, see 'tris+php at tfconsulting dot com dot 
+		// au' comment here: 
+		// http://www.php.net/manual/en/function.defined.php#89886
+		defined($name) or define($name, $value);
+	}
+
+	// Require tunables.php to define tunable constants (That may have 
+	// already been denied in config.php)
+	require_once 'tunables.php';
+
 	if (DB_TYPE == "pgsql") {
 		define('SUBSTRING_FOR_DATE', 'SUBSTRING_FOR_DATE');
 	} else {
diff --git a/include/sanity_config.php b/include/sanity_config.php
index d6be42f26..cb1c1e8ca 100644
--- a/include/sanity_config.php
+++ b/include/sanity_config.php
@@ -1,3 +1,3 @@
-<?php # This file has been generated at:  Mon Apr 1 15:06:12 IDT 2013
+<?php # This file has been generated at:  Mon Apr 1 18:30:54 IDT 2013
 define('GENERATED_CONFIG_CHECK', 26);
-$requred_defines = array( 'DB_TYPE', 'DB_HOST', 'DB_USER', 'DB_NAME', 'DB_PASS', 'MYSQL_CHARSET', 'SELF_URL_PATH', 'SINGLE_USER_MODE', 'SIMPLE_UPDATE_MODE', 'PHP_EXECUTABLE', 'LOCK_DIRECTORY', 'CACHE_DIR', 'ICONS_DIR', 'ICONS_URL', 'AUTH_AUTO_CREATE', 'AUTH_AUTO_LOGIN', 'FORCE_ARTICLE_PURGE', 'PUBSUBHUBBUB_HUB', 'PUBSUBHUBBUB_ENABLED', 'SPHINX_ENABLED', 'SPHINX_INDEX', 'ENABLE_REGISTRATION', 'REG_NOTIFY_ADDRESS', 'REG_MAX_USERS', 'SESSION_COOKIE_LIFETIME', 'SESSION_CHECK_ADDRESS', 'SMTP_FROM_NAME', 'SMTP_FROM_ADDRESS', 'DIGEST_SUBJECT', 'SMTP_HOST', 'SMTP_PORT', 'SMTP_LOGIN', 'SMTP_PASSWORD', 'FEED_FETCH_TIMEOUT', 'FEED_FETCH_NO_CACHE_TIMEOUT', 'FILE_FETCH_TIMEOUT', 'FILE_FETCH_CONNECT_TIMEOUT', 'CHECK_FOR_NEW_VERSION', 'ENABLE_GZIP_OUTPUT', 'PLUGINS', 'CONFIG_VERSION'); ?>
+$requred_defines = array( 'DB_TYPE', 'DB_HOST', 'DB_USER', 'DB_NAME', 'DB_PASS', 'MYSQL_CHARSET', 'SELF_URL_PATH', 'SINGLE_USER_MODE', 'SIMPLE_UPDATE_MODE', 'PHP_EXECUTABLE', 'LOCK_DIRECTORY', 'CACHE_DIR', 'ICONS_DIR', 'ICONS_URL', 'AUTH_AUTO_CREATE', 'AUTH_AUTO_LOGIN', 'FORCE_ARTICLE_PURGE', 'PUBSUBHUBBUB_HUB', 'PUBSUBHUBBUB_ENABLED', 'SPHINX_ENABLED', 'SPHINX_INDEX', 'ENABLE_REGISTRATION', 'REG_NOTIFY_ADDRESS', 'REG_MAX_USERS', 'SESSION_COOKIE_LIFETIME', 'SESSION_CHECK_ADDRESS', 'SMTP_FROM_NAME', 'SMTP_FROM_ADDRESS', 'DIGEST_SUBJECT', 'SMTP_HOST', 'SMTP_PORT', 'SMTP_LOGIN', 'SMTP_PASSWORD', 'CHECK_FOR_NEW_VERSION', 'ENABLE_GZIP_OUTPUT', 'PLUGINS', 'CONFIG_VERSION'); ?>
diff --git a/tunables.php b/tunables.php
new file mode 100644
index 000000000..6de0e2772
--- /dev/null
+++ b/tunables.php
@@ -0,0 +1,28 @@
+<?php 
+	// this file contains default values for various setting that can be 
+	// overridden in config.php
+	// It shoule always be "require()"-d after config.php to allow 
+	// overriding, so please do not "require()" this file directly, it is 
+	// alrady properly included from functions.php
+
+	// **************************************
+	// *** Update proces tuning settings  ***
+	// **************************************
+
+	define_default('FEED_FETCH_TIMEOUT', 45);
+	// How may seconds to wait for response when requesting feed from a site
+	// You may need to decease this if you see errors like "MySQL server
+	// has gone away" pop up in your feed update logs after fetching feeds
+	// from slow websites
+
+	define_default('FEED_FETCH_NO_CACHE_TIMEOUT', 15);
+	// How may seconds to wait for response when requesting feed from a
+	// site when that feed wasn't cached before
+
+	define_default('FILE_FETCH_TIMEOUT', 45);
+	// Default timeout when fetching files from remote sites
+
+	define_default('FILE_FETCH_CONNECT_TIMEOUT', 15);
+	// How many seconds to wait for initial response from website when
+	// fetching files from remote sites
+?>