We've been doing it since 2011, though we saw significant improvements when we switched to 7.x. Memory and CPU usage dropped by ~50% at that time. We did have o

We've been doing it since 2011, though we saw significant improvements when we switched to 7.x. Memory and CPU usage dropped by ~50% at that time. We did have occasionally memory leaks back on 5.6 (usually around shared libraries like libxml) but haven't had any issues whatsoever since 7. I didn't try too much daemonization around ~2005, though Schlossnagle's "Advanced PHP Programming" (2004) did have a whole chapter on daemonizing and the pcntl functions that made it possible.