Optimize get_instance() calls/assignments
diff --git a/system/helpers/cookie_helper.php b/system/helpers/cookie_helper.php
index e465412..5cdcdd1 100644
--- a/system/helpers/cookie_helper.php
+++ b/system/helpers/cookie_helper.php
@@ -59,8 +59,7 @@
 	function set_cookie($name, $value = '', $expire = '', $domain = '', $path = '/', $prefix = '', $secure = FALSE, $httponly = FALSE)
 	{
 		// Set the config file options
-		$CI =& get_instance();
-		$CI->input->set_cookie($name, $value, $expire, $domain, $path, $prefix, $secure, $httponly);
+		get_instance()->input->set_cookie($name, $value, $expire, $domain, $path, $prefix, $secure, $httponly);
 	}
 }
 
@@ -77,9 +76,8 @@
 	 */
 	function get_cookie($index, $xss_clean = FALSE)
 	{
-		$CI =& get_instance();
 		$prefix = isset($_COOKIE[$index]) ? '' : config_item('cookie_prefix');
-		return $CI->input->cookie($prefix.$index, $xss_clean);
+		return get_instance()->input->cookie($prefix.$index, $xss_clean);
 	}
 }
 
diff --git a/system/helpers/html_helper.php b/system/helpers/html_helper.php
index ece3958..988eee7 100644
--- a/system/helpers/html_helper.php
+++ b/system/helpers/html_helper.php
@@ -199,15 +199,13 @@
 		{
 			if ($k === 'src' && strpos($v, '://') === FALSE)
 			{
-				$CI =& get_instance();
-
 				if ($index_page === TRUE)
 				{
-					$img .= ' src="'.$CI->config->site_url($v).'"';
+					$img .= ' src="'.get_instance()->config->site_url($v).'"';
 				}
 				else
 				{
-					$img .= ' src="'.$CI->config->slash_item('base_url').$v.'"';
+					$img .= ' src="'.get_instance()->config->slash_item('base_url').$v.'"';
 				}
 			}
 			else
diff --git a/system/helpers/language_helper.php b/system/helpers/language_helper.php
index 4d571a7..d7aa8e6 100644
--- a/system/helpers/language_helper.php
+++ b/system/helpers/language_helper.php
@@ -52,8 +52,7 @@
 	 */
 	function lang($line, $for = '', $attributes = array())
 	{
-		$CI =& get_instance();
-		$line = $CI->lang->line($line);
+		$line = get_instance()->lang->line($line);
 
 		if ($for !== '')
 		{
diff --git a/system/helpers/security_helper.php b/system/helpers/security_helper.php
index 4bb94a2..7a6df54 100644
--- a/system/helpers/security_helper.php
+++ b/system/helpers/security_helper.php
@@ -49,8 +49,7 @@
 	 */
 	function xss_clean($str, $is_image = FALSE)
 	{
-		$CI =& get_instance();
-		return $CI->security->xss_clean($str, $is_image);
+		return get_instance()->security->xss_clean($str, $is_image);
 	}
 }
 
@@ -66,8 +65,7 @@
 	 */
 	function sanitize_filename($filename)
 	{
-		$CI =& get_instance();
-		return $CI->security->sanitize_filename($filename);
+		return get_instance()->security->sanitize_filename($filename);
 	}
 }
 
@@ -107,8 +105,7 @@
 	 */
 	function strip_image_tags($str)
 	{
-		$CI =& get_instance();
-		return $CI->security->strip_image_tags($str);
+		return get_instance()->security->strip_image_tags($str);
 	}
 }
 
diff --git a/system/helpers/url_helper.php b/system/helpers/url_helper.php
index b0f4368..2d92897 100644
--- a/system/helpers/url_helper.php
+++ b/system/helpers/url_helper.php
@@ -91,8 +91,7 @@
 	 */
 	function current_url()
 	{
-		$CI =& get_instance();
-		return $CI->config->site_url($CI->uri->uri_string());
+		return get_instance()->config->site_url($CI->uri->uri_string());
 	}
 }
 
@@ -109,8 +108,7 @@
 	 */
 	function uri_string()
 	{
-		$CI =& get_instance();
-		return $CI->uri->uri_string();
+		return get_instance()->uri->uri_string();
 	}
 }
 
@@ -127,8 +125,7 @@
 	 */
 	function index_page()
 	{
-		$CI =& get_instance();
-		return $CI->config->item('index_page');
+		return get_instance()->config->item('index_page');
 	}
 }