I used to code in Java for the Dynamo Server platform. Just to set it up was a pain and we spent days and days just to set it up.
PhP is a cheaper solution and is my preference. I have looked at Zope engine and it is something to look into again.
Or typo3.com engine.
But - all this drama about performance. If I want better performance - I just spend another $200 and get DDR2 memory and SATA hard drive. Hey - its quicker now.
The gaming industry is pushing for faster CPUs, Faster Hard drives and Memory so when it comes to performance - just get a new AMD Athlon XP, DDR2, SATA hard drive and you are good to go!!!