My game is very slowly run

Hello, i have problem My NFS Undercover game is very slow i can't play


My System

Processor: Pentium(R) Dual-Core CPU E5300 @ 2.60GHz (2621 MHz)
Operating System: Microsoft Windows XP (Service Pack 2)
DirectX version: 9.0c
GPU processor: GeForce 8400 GS
ForceWare version: 171.37
Memory: 512 MB
Video BIOS version: 62.98.3c.00.00
IRQ: 16
Bus: PCI Express x1


So why my game Run very slow

Please Help