Cubase 6.5 Sluggish Gui


after some time i went back to C6 on my Mac Pro early 2008, 24GB Ram, made an arrangement of roughly 30 tracks, 1 external Instrument, 2 VST´s, the rest is Audio.
I was working with a lot of small cuts, ending up in turning them into larger Parts from small events.
The Gui went sluggish, zoom is very slow even using by the mouse drag.
I adress this behaviour back to C4 or even C3. Being C6 now considered as " Legacy Version “, was this issue ever beeing resolved or is there anything what i can do on my side to make it work better ? Upgrading is not an option right now because of the” loud Fan noise " behavior on 10.8 after upgrading my OS from 10.6 i had to go back to Snow Leo, preventing myself from being disturbed by my Mac sounding like a vacuum cleaner.

Can anyone confirm this ?
I know i´m a bit late since we are already on V8 but i can´t believe that this is still present.
I even made a screen capture during the zooming in the Arrange Window.

My System: MacPro early 2008
2x2.8 GHz Quad Core Xeon, 24GB Ram, OSX 10.6.8, 2x ATI Radeon HD 2600 XT, 3 Monitors connected: 1x Dell U2713HM, 2x Phillips 200W