Tried it in PHP v8 (on Windows): .\php fib.php 1402.1289348602 ms and with PHP8's new JIT opcache on: .\php -dopcache.enable_cli=1 -dopcache.jit_buffer_size=

Tried it in PHP v8 (on Windows): .\php fib.php 1402.1289348602 ms and with PHP8's new JIT opcache on: .\php -dopcache.enable_cli=1 -dopcache.jit_buffer_size=200M fib.php 219.55609321594 ms