You'd go about using pthreads, so I think you should have a look at this guide first: http://pthreads.org/tutorials/start.html
Oh that's strange. Recently there are crashs being reported on pthread's GitHub issue tracker: https://github.com/krakjoe/pthreads/issues/180 Could you try again with the latest pthreads dll? Here they describe the installation for Windows PHP installations, you may apply it to your PM-MP's php directory
Do you have a test server? I'd suggest setting up a simple LAMP instance in VirtualBox or VMWare for that purpose.
I'm able to run my Timer plugin in PHP using my system's PHP installation. It should be worth a try to test your script in another environment
Maybe I can just make a pre-generated world and when I wanna generate it, I just tp all players to spawn, unload the world, remove world folder and copy pre-generated folder in and load it back!