Cursor movement in ttstpdisplay and debugger is a matter of feeding extra commands to a bshell that might be very busy doing all kind of things already on a occupied system (other user processes). The cursor movement does not get a high priority.
Use pagedown / pageup to be somewhat quicker, then you do not need to rebuild the display with every new feeded line, but in page mode.
In the debugger you can jump to lines with v 100 (view line 100), in the display you can jump to specific pages (G for GotTo) or to the end (B for bottom) or read the tail of a building file with R.
Also read Luke 24:4-8