FPS by configuration

I just wish there was a web page somewhere on the internet that could give me a rough estimate of the frame rate a particular game would achieve on a particular configuration. It needn't even be based on an analysis, because that I know is complicated. Even a small program running in the background may cause the game to fall below the threshold value of RAM usage and the game may end up reserving much smaller RAM footprint thereby decreasing the FPS drastically. I'm suggesting something that could very well be based on empirical data. Users upload their achieved FPS in lieu of some freeware. Would be a boon to people with moderate rigs when choosing game to play or people buying hardware to play a particular game. There are just too many games out there. Even after reading reviews and following ratings, there are still too many to be played as demos. I wish all of this could be available on a single website ... ratings, reviews, FPS by config.