--------------------------------------------------------------------------------------------------------------------------
WARNING: This guide assumes your PC can run Dead Space and far exceeds its minimum requirements. NO AMOUNT OF TWEAKING will fix lag/stutter if your machine can't handle the game/has trouble running the game. This guide assumes the lag is because of Visceral's refusal to patch out the inherent mouse lag problem, not because of a PC that has lackluster components. That said, here's the video:
--------------------------------------------------------------------------------------------------------------------------

https://www.youtube.com/watch?v=M9lMhyRr8Go

VTL;DW (video too long; didn't watch):

1. Go to your video card's control panel.

2. Make sure the Vsync setting of Dead Space isn't set to "application setting" or "Off." Turn on Vsync from there.

3. Launch the game and turn off Vsync from the ingame options menu.

Enjoy a lag-free experience!

--------------------------------------------------------------------------------------------------------------------------
NOTE: The video shows the Nvidia Control Panel. Owners of PCs having AMD-ATI video cards should not worry. Simply go into your video card's control panel and hunt for AMD-ATI's version of "Vsync." If they're using the same term well, well and good. If not there HAS TO BE an equivalent setting in there somewhere. Good luck!
--------------------------------------------------------------------------------------------------------------------------

If this helped in any way, please don't forget to rate this with a thumbs up! Happy gaming!

BONUS TIP:

If you've Mass Effect 3 and Dead Space 3, you can unlock the N7 armor. Here's my guide on how to get the N7 suit in Dead Space 3:

https://www.youtube.com/watch?v=xuo53e3kCsg

(If you've uninstalled Mass Effect 3, ME3 save files and instructions on where to put them are included.)