I know thats what i ment with usually you give a fuck, i dont know any way you could run PHP single threaded on a server (i mean there sure is). But its something common you learn when you programm in the other languages i mentioned.

I dont think it could get a real issue in a real environment, except someone really wants to fuck with you. But the some fail2ban on to fast requests should fix this easily as the hashes dont actually take that long.