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.