Graphics Lag when multiple Sliced audio parts present


I have been having graphics lagging problems with Cubase 6. I have read the topics about this issue here as well.
I have realized that when I have lots of audio parts that contain sliced audio events inside Cubase’s graphics become slow and laggy when you move your mouse cursor up and down over them. As soon as I delete the parts the graphics become responsive again. At first I thought it was a plugin causing the problem but after I removed the sliced audio parts everything was back to normal.
Also, using the crosshair for the tools makes Cubase graphics laggy as well.
I include a screenshot of the parts that cause the problem each time.

I have purchased the 6.5 update for Cubase but I am still at version 6.05.
Are in any case these graphics problems solved in the 6.5 update?

My graphics card is up to date and I don’t get any other issues except for that.
Graphics Lag.PNG