After trying with MangoHud, libstrangle, and GOverlay without any success I found on a Dead Space 1's protondb entry the:

DXVK_FRAME_RATE=60 %command%

If you have VSync on (in-game) it's 30 FPS, and Vsync OFF the FPS jumps up too much and the engine was not meant to run at +60 FPS.
The above command was the only option that worked for me (mango, strangle, goverlay, all worked on other games/apps, but for some reason not on Dead Space 2).