Is my GPU Too weak to handle gta 4 or is it unoptimised?

[sadseada123]

My rig
Intel Core i7-870
6GB DDR3 1600MHZ RAM
650W PSU
MSI GEFORCE GTX 260 CORE 216 1792MB SUPERCLOCKED
OK Now as GTA 4 requires CPU Muscle as well as GPU Ram.I have plenty to feed it.lol
Now when I installed patch 5 the game lags during evenings.The fps goes till 30 with some dips to 25.During rains the fps is ATROCIOUS.It goes up till 25 fps in rains constant.Hell,crysis warhead plays at 25-35 fps at my rez 1680X1050 at enthusiast with 2XAA.During the rest of the day the fps is 40 up constant.These fps points are with patch 5 AND WITH VIEW DISTANCE Traffic density detail distance all at 100.Now when I installed the latest patch 6 and 7.THE GAME SLOWED DOWN SO MUCH THAT I had to lower everything to zero to get at least 40 fps in the game.Is my gpu to weak to handle the game.Will a 460 solve this problem?

 

[wa1]

No, you will see the same problem with GTX460 or even HD5970.
GTA 4 is a BAD coded game, even a HIGH END gaming PC would still struggle to handle this game...