That's just because the higher quality graphics slow the game's FPS down. If you want it to run faster, try turning off the optional effects (Fluid Blood, Reflections, Soft Shadows), or upgrade your PC. There appears to be a limit on the FPS the game can run at with shaders on anyway, so it'll always be a little slower.
"Call yourself alive? I promise you you'll be deafened by dust falling on the furniture,
you'll feel your eyebrows turning to two gashes, and your shoulder blades will ache for want of wings."
you'll feel your eyebrows turning to two gashes, and your shoulder blades will ache for want of wings."
