Make requests faster by faster IO operations (eg file_exists is slower compared to is_file) #16552
Description
See https://bugs.php.net/bug.php?id=78285
From https://thephp.cc/news/2020/10/caching-makes-everything-faster-right
We’re probably having several hundred file_exists calls per request so replacing this calls with is_file could speed things up. Especially where the disk is slow or where there's heaps of traffic.