20-25 fps in Siberia!!! (Syberia)

In game 1 my fps is somewhere between 20 and 25
my computer is powerful enough to wydawania 60 - 120 fps in this game
here you characteristics of my computer
Features Cuideachta: NVIDIA GeForce GTS 450
CPU: Intel(R) Pentium(R) CPU G860 @ 3.00 GHz
RAM: 4 GB
Windows 8.1
You understand Siberia requires:
Requirements for the game Syberia 1O: Windows XP/Vista/7/10.
Processor: 1 GHz
RAM: 512 MB
Disk space: 1.2 GB free space
Video card: 128 MB VRAM compatible with DirectX.
DirectX: 9.0 c.
Sound card: compatible with DirectX 9.0 c.