I realize this subject is not black and white and has quite a bit of depth to it as high usage of either the CPU or RAM does not necessarily mean that a computer is running slowly.
However, is there any documentation, scientific research or academic journal that makes a correlation between poor system performance and the consumption of system resources.
It goes without saying that if you use all your RAM then there won't be any available for additional programs, but can this be substantiated with metrical data?