I've seen the performance improvements in PHP 7, which look awesome, and it's good to know that there are modern frameworks available now, so it's entirely poss

I've seen the performance improvements in PHP 7, which look awesome, and it's good to know that there are modern frameworks available now, so it's entirely possible the PHP universe has improved markedly since I was there last. But what kills PHP for me (and Rails and Django, for that matter) is the lack of native support for asynchronous operation and poll/epoll. If you're stuck with one thread per user, then you can't scale beyond a couple thousand concurrent users on one system without latency getting terrible. You can just do so much more on one server with Node it's not even funny. 70k queries per second with low latency are not uncommon; add in some work and that goes down, of course, but a well written app can have 20k+ queries per second of throughput. Even PHP 7 with WordPress in cached mode only brags of ~5k queries per second. You could likely do 4x that in Node without trying -- and possibly even without caching.