I don't have P2007 installed but I wouldn't say the scrolling issue is new to P2007 -- I've had the same problem since P98.
I've never found a satisfactory workaround but this one "sorta" works. (This works best if you have only one schedule open.)
Maximize the screen
Window > new window
You'll see the currently open file name; click on OK. If you have multiple files open then choose the current file and click on OK.
Window > Arrange all
If you have one file then you'll see two windows one above and one below. If you have multiple windows you'll have to take the two that you want and resize them so that they are the only two visible. (Well, you can still display the others but they're just eating up screen real estate and getting in the way.)
In "Window1" position the screen so you can see where you want the lines to go.
In "Window2" highlight the lines you want to move. To highlight, click on the first line, hold down the shift key and use the up (or down) arrow to select additional rows
Place the cursor in the grey ID column within the highlighted rows, hold down the LeftMouseButton and drag the rows from Window2 to Window1. You will see the little "+" sign indicating you are making a copy -- there is no way that I have found to make this a move.
Switch back to "Window1" (where the source lines are still highlighted)
Press the delete key once.
There is a serious drawback to this workaround which may or may not impact your work -- it depends on some of your internal processes. The UniqueID field will be changed. If you have systems interfacing with your project schedules and they are using the UniqueID field then you will lose the "connection."
The advantage is that this eliminates the highspeed scroll as you move to the destination location.