I got the same issue after I updated 0.49. + The mouse cursor was laggy and showed it position only after I clicked somewhere.
EDIT: Found a quickfix, just go to your C:/Users/Username/Documents/DayZ and open DayZ.cfg with notepad and edit the resolution values to match yours. If you are not sure what to do, just google "dayz config resolution" and its like first link in the list "[FIX] "Pixelation" and other resolution problems. " It made my game playable.