Cubase 6 64bit uses more CPU than Cubase 5 32bit (!?)

i’ve just installed the cubase 6.54 64bit version and by first loading some older cubase 5 projects showed cpu overload… i bought the jbridge and managed all my 32bit/64bit plugins… that worked fine and i could open the older projects without overlaod. BUT STILL, if i compare the CPU usage of the same project cubase 5 (32bit) used only 40%, cubase 6 (64bit) a bit more than 50%…
i’m using the lynx l22 pci audio card.
anyone a solution to this problem or is this just the way it is???