From stretch component/php72 we have php-xdebug 2.7.0-1+wmf1 and it has some performance issue doing way too many `getpid` calls.
Upstream issue: https://bugs.xdebug.org/bug_view_page.php?bug_id=00001641
I thus could use an upgrade to xdebug 2.7.1, or at least the inclusion of upstream commit https://github.com/xdebug/xdebug/commit/df17570fd52846baa7134f350547970644a8d1d5
Xdebug is used for generating PHPUnit code coverage report. I noticed the issue while doing a system wide perf showing:
```
Samples: 34K of event 'cpu-clock', Event count (approx.): 346343430880
Overhead Command Shared Object Symbol
85.31% swapper [kernel.kallsyms] [k] native_safe_halt
3.77% php [kernel.kallsyms] [k] __bpf_prog_run
2.04% php libc-2.24.so [.] __getpid # <<------ OOPS
0.84% php xdebug.so [.] 0x00000000000165d5
0.84% php xdebug.so [.] 0x000000000001665b
```
And found the upstream bug report by pure luck :]