when logging in that the server load spikes to 99% CPU

I am using elgg-1.8.19 . URL : https://safalaya.com . When someone is logging in the website the server load spikes to 99% CPU . I have also noticed the below error repeating and filling up the below error_log.

root@server [/home/mramsey]# tail -f /home/nsikdar/public_html/error_log
[29-Mar-2020 11:51:33 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:51:38 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:52:24 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:52:28 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:53:21 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:53:24 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:54:19 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:54:39 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:54:51 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6
[29-Mar-2020 11:55:52 UTC] PHP Deprecated: ini_set(): Use of mbstring.internal_encoding is deprecated in /home/nsikdar/public_html/engine/lib/mb_wrapper.php on line 6

I am giving you the contents of my mb_wrapper.php file .

<?php
 
// if mb functions are available, set internal encoding to UTF8
if (is_callable('mb_internal_encoding')) {
mb_internal_encoding("UTF-8");
ini_set("mbstring.internal_encoding", 'UTF-8');
}
 
/**
 * Parses a string using mb_parse_str() if available.
 * NOTE: This differs from parse_str() by returning the results
 * instead of placing them in the local scope!
 *
 * @param string $str The string
 *
 * @return array
 * @since 1.7.0
 */
function elgg_parse_str($str) {
if (is_callable('mb_parse_str')) {
mb_parse_str($str, $results);
} else {
parse_str($str, $results);
}
 
return $results;
}
 
 
 
/**
 * Wrapper function for mb_split(). Falls back to split() if
 * mb_split() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_split() {
$args = func_get_args();
if (is_callable('mb_split')) {
return call_user_func_array('mb_split', $args);
}
return call_user_func_array('split', $args);
}
 
/**
 * Wrapper function for mb_stristr(). Falls back to stristr() if
 * mb_stristr() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_stristr() {
$args = func_get_args();
if (is_callable('mb_stristr')) {
return call_user_func_array('mb_stristr', $args);
}
return call_user_func_array('stristr', $args);
}
 
/**
 * Wrapper function for mb_strlen(). Falls back to strlen() if
 * mb_strlen() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_strlen() {
$args = func_get_args();
if (is_callable('mb_strlen')) {
return call_user_func_array('mb_strlen', $args);
}
return call_user_func_array('strlen', $args);
}
 
/**
 * Wrapper function for mb_strpos(). Falls back to strpos() if
 * mb_strpos() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_strpos() {
$args = func_get_args();
if (is_callable('mb_strpos')) {
return call_user_func_array('mb_strpos', $args);
}
return call_user_func_array('strpos', $args);
}
 
/**
 * Wrapper function for mb_strrchr(). Falls back to strrchr() if
 * mb_strrchr() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_strrchr() {
$args = func_get_args();
if (is_callable('mb_strrchr')) {
return call_user_func_array('mb_strrchr', $args);
}
return call_user_func_array('strrchr', $args);
}
 
/**
 * Wrapper function for mb_strripos(). Falls back to strripos() if
 * mb_strripos() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return int
 * @since 1.7.0
 */
function elgg_strripos() {
$args = func_get_args();
if (is_callable('mb_strripos')) {
return call_user_func_array('mb_strripos', $args);
}
return call_user_func_array('strripos', $args);
}
 
/**
 * Wrapper function for mb_strrpos(). Falls back to strrpos() if
 * mb_strrpos() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return int
 * @since 1.7.0
 */
function elgg_strrpos() {
$args = func_get_args();
if (is_callable('mb_strrpos')) {
return call_user_func_array('mb_strrpos', $args);
}
return call_user_func_array('strrpos', $args);
}
 
/**
 * Wrapper function for mb_strstr(). Falls back to strstr() if
 * mb_strstr() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return bool
 * @since 1.7.0
 */
function elgg_strstr() {
$args = func_get_args();
if (is_callable('mb_strstr')) {
return call_user_func_array('mb_strstr', $args);
}
return call_user_func_array('strstr', $args);
}
 
/**
 * Wrapper function for mb_strtolower(). Falls back to strtolower() if
 * mb_strtolower() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_strtolower() {
$args = func_get_args();
if (is_callable('mb_strtolower')) {
return call_user_func_array('mb_strtolower', $args);
}
return call_user_func_array('strtolower', $args);
}
 
/**
 * Wrapper function for mb_strtoupper(). Falls back to strtoupper() if
 * mb_strtoupper() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_strtoupper() {
$args = func_get_args();
if (is_callable('mb_strtoupper')) {
return call_user_func_array('mb_strtoupper', $args);
}
return call_user_func_array('strtoupper', $args);
}
 
/**
 * Wrapper function for mb_substr_count(). Falls back to substr_count() if
 * mb_substr_count() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return int
 * @since 1.7.0
 */
function elgg_substr_count() {
$args = func_get_args();
if (is_callable('mb_substr_count')) {
return call_user_func_array('mb_substr_count', $args);
}
return call_user_func_array('substr_count', $args);
}
 
/**
 * Wrapper function for mb_substr(). Falls back to substr() if
 * mb_substr() isn't available.  Parameters are passed to the
 * wrapped function in the same order they are passed to this
 * function.
 *
 * @return string
 * @since 1.7.0
 */
function elgg_substr() {
$args = func_get_args();
if (is_callable('mb_substr')) {
return call_user_func_array('mb_substr', $args);
}
return call_user_func_array('substr', $args);
}

Please tell me how can I solve this problem .