What could cause a decent computer to run a game poorly?

[Eroge]

What different possibilities are there that could cause a computer with good enough specs, to run a game poorly?

I ask because every game forum I go on, in the Technical section there are people with nice i5/i7s, and expensive video cards yet for some reason they get low FPS. No one ever seems to be able to help them so they blame the game

My hardware isn't the best, but people with worse computers are able to play games I'm not.
I'll go to play a game and will get 20fps when my graphics are set to high. So I then lower everything to its lowest and will still get under 30fps. The only thing anyone ever says to do is "update the video card drivers." So I get the latest beta driver for my GTX 460 but the FPS in game remains the same

What else could cause someone to get unusual FPS in a shitty game? I want to look at everything and not just the video card

 

[hdeezie80]

Shitty programming on the developers part, look for a config file to edit, there are usually certain tweaks that can drastically improve performance. There will always be shitty console to PC ports like GTA IV or Darksiders 2. Also good to keep your drivers up to date. Overclocking can greatly increase performance as well, make sure you know what you are doing, and are comfortable poking around in your computers BIOS though, it is pretty easy to burn out hardware if you don't pay attention to what your doing.

 

[JDFan]

Too many variables to list without knowing more info. What Game -- What settings - What system specs -- all of them combine to make the results and any one could be the weak link causing the poor performance.

With PC gaming it is all about balance and keeping all of the parts performing at the same level -- ie. if you have a 1 GB. VRAM video card and use settings that require loading more than 1 GB. of textures and after effects into memory performance will drop due to using the cache memory of the system rather than the video Ram which is much faster -- using a slow HDD with small cache or slow access times can result in the system waiting for information to load -- etc. etc.

You say your system isn't the best but what parts of it are holding it back is impossible to say without specifics.