I have a couple friends who worked on a FedEx shipping site a few years ago. It was built using PHP. (They think it still is)
I'm a veteran PHP, Java and C#.Net developer. (I do C# now and did Java for 8 years for my day job) I'd put any of my PHP sites up against any of my Java sites and the performance of PHP would run circles around Java. In my experience, Java requires WAY more resources to run enterprise apps. (I've spent way too many hours into tweaking WebSphere to not bog down and die) Not sure what you worked on in Java, @jirdw but it must have been pretty light.
You also got really lucky running your 11 year old code on modern Java EE. Anything substantial we did would often break with the next EE release which almost always contained breaking changes. I worked in the Java world for 8 years, from Java 5 - 8. Can't say I miss it.