Technical issues v.1 (Dead Space 3)

The thing is: sometimes the game freezes. Approximately once every minute or two. It hangs for a second, and sometimes for two or three.
Along with this, the sound hangs: one word is played several times.
My conf:
Windows 7 ultimate SP-1.
Nvidia Geforce 9800-GT
Pentium(R)Dual-core.
4 gigs on board.
Yes, I know that the computer is ancient, but it seems to fit. I urgently need help, I tried everything. Even at the lowest settings, it lags, although the previous two flew without a hitch.