The one big problem of Java is its unpredictable latency, mostly due to the caching status of the JIT compiler. If the bit of code you need for smooth scrolling is already in the cache, its fast and otherwise it's slower. There's also the occasional garbage collect which really locks the whole thing.There are some attempts to make Java interpreters more predictable but to me they feel like an awful hack, trying to force Java into something it was never meant for.
I have actually tried extremely simple programs using swing, awt, swt and qt-jambi, and all of them jitter when showing a tickertape. The same qt program in C++ does not jitter. So I stand by my point of view. Don't believe me; try it yourself.
As for fanboyism; you asked for it with you 'miles better'. It's not, it's just different and far less integrated and not as fast as Qt. And it's Java, so it doesn't start quick, and is not really quick (compare Eclipse with Qt-Creator for instance). Have you even worked in Qt? I have, and in Java + AWT, Swing, Swt and even Qt. Oh and about two dozen other languages.