Slow Respond in games on higher resolution

Slow Respond in games on higher resolution such as 1366x768 or 1024x768

System Specification :

Processor - Intel Pentium (R) Dual Core 2.50 Ghz
RAM - 2 GB/800
Graphics - 1 GB Zoatc Nvidia Geforce 8400 GS DDR2
Keyboard - Logitech Internet Pro Desktop Black

Cause some delay in game respond mainly in racing games like - NFS Hot Pursuit 2010
but games runs at 28 - 30 fps. gameplay is smoother but i experience a delay in response such input device like keyboard.

Any Help ?

Your system really won't handle many modern games at good resolutions. When a system is being pushed and doesn't even hold a steady 30fps, you'll usually notice a lot of keyboard and mouse input lag too. Running a game at a 'playable' level means it has to hold no less than 30fps 100% of the time, if it dips below that but average fps is ~30-35fps, that's still not playable. The easiest thing for you to do is go out and grab a nicer graphics card. You can easily quadruple your power with even a $100 new one.

but i get good respond in cod mw 3 and cod mw Optimal System Settings @ 40 - 60 fps

Honestly that's comparing apples and oranges. You can run Doom 3 at 200fps with no input lag, but try Crysis 3 and you'll chug along like a dying train going uphill on its last piece of coal. They're not the same thing.

Some games have a specific type of input lag that I'm not 100% what the cause is, but it directly correlates to system performance. Resident Evil 5 is great at looking okay at 30fps, and taking a full half second to respond to a mouse swipe or keystroke. Lots of racing games do it too. Grand Theft Auto 4 is another huge offender. But it always happens when framerates aren't at healthy ranges. I assume it's the game engine that's the culprit, but with increased framerate comes quicker input speed. All I can say is you should upgrade.

What type of upgrade i need ???

(graphics card)

and RAM if you're looking at upgrades. If you've got a budget I'd be happy to even look some up for you.

man i m belong to middle class family i cant afford too much on gpus and rams also