I'm not saying it's not faster - I'd expect some (maybe many) JVM scenarios to be faster than PHP. But "PHP is slow" is just not a real world problem for most

I'm not saying it's not faster - I'd expect some (maybe many) JVM scenarios to be faster than PHP. But "PHP is slow" is just not a real world problem for most use cases of PHP in web applications. Running your business 15-20% faster will not be enough of a compelling argument for people to switch to an entirely new toolchain and way of thinking. I give you Ruby and JRuby as one major example. Using JPHP as a way to get PHP running on Android, if it's seamless and strong experience, would be something to focus more efforts on, imo. Every single successive version of the JVM being 30% faster is simply not born out in the real world across the board. I ported JVM web apps from JDK 6 -> 7 -> 8, and didn't see anywhere near those performance increases. Does the JVM improve with each iteration? Sure. So does PHP, and PHP7 is going to be a huge across the board improvement, but I doubt we'll see this sort of doubling of performance from a single release any time soon after PHP7 release.