It's not that it isn't optimized, it's that it does 50 (FIFTY! Really!) database queries for a blank front page. The fact that Nukes is faster isn't so much because it's so speedy, but because it chose to race against the fattest, slowest thing around.
You have to understand that (PHP|Post)Nuke is geared towards the lowest common denominator, like all sorts of other PHP apps. It can be installed easily in a $9/mo shared hosting environment by anyone with about five minutes of free time.
Yes, it sucks for just about everyone, but if one makes the assumptions that you have to make with Nukes (not the least of which is a dedicated box, no shared host will let you run a 60+MB process 24/7) you could come up with a comparable solution in PHP as well.
I'm definitely not a "PHP lover" by any stretch of the imagination, but JBoss is being kinda lame by picking on the retarded kid.