Improved Performance of processResponse

As bin2hex is a bit slow, only parse the start of the string

src/WooCommerce/HttpClient/HttpClient.php

@@ -363,7 +363,7 @@ protected function processResponse()
     {
         $body = $this->response->getBody();
 
-        if (0 === strpos(bin2hex($body), 'efbbbf')) {
+        if (0 === strpos(bin2hex(substr($body, 0, 4)), 'efbbbf')) {
             $body = substr($body, 3);
         }