Beachball when using Markers

I have been noticing that on occassions that when I am in the Marker window and am say Marker 3, but want to Shift-Tab (reverse) back to Marker 2, it will then beachball and I have to force quit the program and come back in again.

Also, there are times when the only program running is Cubase and it can go quite slow, taking a lot longer to redraw and catch up to what’s playing in real time.

I’ve also enountered moments when I use the Scissor tool (which is a lot) and I can’t see the cursor/line over where I want to cut.

I’m running 10.6.8 on a 27’ iMac, 6.0.3 Cubase. I’ve unticked “Run in 32-bit mode”, will that now go to 64 or is it only in Lion that it’s possible ?