[php-src] Issue #11037: HTTP echo/output/cli webserver is quite slow

Issue: https://github.com/php/php-src/issues/11037 Author: mvorisek ### Description The following code: ```php <?php $sizeMb = 1024; $sizeBytes = $sizeMb * 1024 * 1024; header('Content-Type: application/octet-stream'); header('Content-Length: ' . $sizeBytes); header('Content-Disposition: attachment; filename="test.bin"'); $string = str_repeat(bin2hex(random_bytes(128)), 256); // 64 kB for ($i = $sizeBytes / strlen($string); $i >= 0; $i--) { echo $string; } ``` Webserver cmd: ``` php -S 1.2.3.4:9687 -t dir_path ``` Speedtest cmd: ``` wget -O/dev/null http://1.2.3.4:9687/test.php ``` Resulted in this output: ``` HTTP request sent, awaiting response... 200 OK Length: 1073741824 (1.0G) [application/octet-stream] Saving to: ‘/dev/null’ /dev/null 100%[=================================================>] 1.00G 159MB/s in 6.6s 2023-04-08 01:01:38 (156 MB/s) - ‘/dev/null’ saved [1073741824/1073741824] ``` But I expected this output instead: We have a PHP app that can stream data at several GB/s, but as shown in the example above, PHP HTTP echo/output/cli webserver is quite slow and I cannot get above about 150 - 170 MB/s. Based on CPU usage I belive the bottleneck is in PHP and it is possible to improve it. I would expect 1+ GB/s speed. ### PHP Version * ### Operating System tested on Windows and linux