A typical BDM transaction between the debugger and the target goes like this. Debugger requests a memory-read from target. Debugger polls target for end of read. Target indicates to debugger that the memory-read is complete.
Target passes memory-read results to debugger.
The problem is that a memory-read on a bad address causes a bus fault error. So the polling routine must time-out before it can terminate. This time-out takes a long time, resulting in very slow window update speeds. The solution is to scroll the window so that bad memory is not visible. This problem occurs only when the code contains local variable pointers.