need help please

Hi!

my nba 2k10 is lagging during playing a game but not on menu and practice dont know why

my specs are as follows:

Windows 7 x86(32Bit)
AMD athlon(tm) 64 X2 Dual Core Processor 4600+(2CPUs), ~2.4ghz
2Gig Of Ram
GeForce 9500GT dd3 total memory of 1.7gig
Direct x11(Direct3d 11)
250Gig HD

My Settings In Game are as follows:
1024x840 85 refresh rate
player detail: low(not lagging) high(lagging)
Arena: High
Texture: High
Depth of Field: on
Floor Reflection: on
SideLine Characters: on
fps is always at 15-16

i didnt turn on the anti-aliasing in the game and v-sync is of

and everything in my nvidia control panel is in default

and everything in my drivers are up to date according to driver genius professional


thanks