As for QT creator: Does it support other components? (like gtk2 or gtk3?).
Pure bullshit. Java is much faster than Mono. Not a bit faster, but A LOT faster. In fact, it's the third fastest language after C and FORTRAN. And unlike C#, it's really cross platform.
Maybe they got better in version 7 (that'd explain the result of the website). I've to take a closer look at what that 'benchmark' does and how it was implemented.