I recently upgraded my RAM on my small laptop from 1 to 2 GB. Before and after the upgrade I have been paying attention to the physical memory percentage indicated at the bottom of the Windows Task Manager. Before the upgrade, it was in normal use (i.e. NOT under heavy load) at about 80% (and under heavy load it approached 99%). Now with 2 GB RAM it is in normal use at about 50%-60% and the computer feels more responsive.
Thus, my question: What is the optimal percentage in terms of speed and performance that physical memory should be used? Is it so that the lower the percentage, the faster the computer responds? Or is it so that if I were to upgrade my laptop now to 3 GB (and correspondingly the physical memory percentage would go down to about 30%), my computer would not be any faster?
I might ask my question also the other way round: If I know that I need x amount of RAM memory in normal use, how much memory should I have in total? X times two? X plus 10%? Or X times three? I hope you get my point :)
Looking forward to your answers!
P.S. I am NOT asking this question because of the laptop that I have now (as the max RAM it can handle is already 2 GB anyway) but because I am (still) in the process of buying a new better laptop for Photoshopping and such things. My related question about which CPU I should choose is here: http://www.makeuseof.com/answers/choose-intel-core-i5-i7-processor-laptop/