After upgrading yii2 version, api requests are processed slower

After I updated Yii2 from 2.0.14 to 2.0.50, API requests started executing 20% - 30% slower.

public function makeApiRequestLogic()
return true;

Can you try to find why?

After the update, two new headers appeared. Could this be a problem?

YII 2.0.14

YII 2.0.50

Thanks for the information.
Do you use any kind of proxying? Can you reproduce same issue with Apache Httpd?

No, I don’t use a proxy. Instead of Apache, Nginx was employed.

Can you test latest master?