[samsonasik]

This PR improve parallel process performance by using pcntl_fork when possible, as a forked worker is a copy of the already initialized PHP process, so it can start working right away, see my post at dev to that I applied the performance improvement on StructArmed via pcntl_fork when possible:

https://dev.to/samsonasik/structarmed-fast-php-architecture-guards-you-can-rely-on-3be3#an-even-faster-parallel-process

Measured with bench/parallel_memory_bench.php, 8 workers, 3 cold runs each, PHP 8.4, same php.ini with PHPStan Turbo loaded on both sides:

Project	Metric	main (spawned workers)	this PR (forked workers)
CodeIgniter4 system	CPU (user+sys)	19.1–20.0 s	16.6–17.0 s
	Peak total RSS	2125–2210 MiB	1974–2017 MiB
	Peak single worker RSS	294–314 MiB	274–281 MiB
	Changed files (fingerprint)	257	257
spiral-framework src	CPU (user+sys)	11.9–12.6 s	9.7–9.8 s
	Peak total RSS	1812–1889 MiB	1693–1720 MiB
	Peak single worker RSS	244–258 MiB	231–236 MiB
	Changed files (fingerprint)	137	137

Without PHPStan Turbo loaded in the main process, workers are still spawned and nothing changes.

[samsonasik]

@TomasVotruba ready 👍