I posted the same thread on a different forum, so I'll just copy the text: Firstly, I would like to praise the community of this forum for all the advice and information I have received whilst researching solutions for my many issues over the years. I have always been able to resolve the problems through such research, yet in this case, I find myself in a stalemate. Anyway, my problem is as follows: I own a MacBook Pro 13" mid 2010 (2.4Ghz, 4Gb Ram), running Lion (Clean install), and whenever I use apps that are CPU and RAM-heavy, the system feels really sluggish and turns the mouse pointer into the beach ball more often than I care to endure. I started to investigate inside Activity Monitor and found the Page Ins/Page outs ratio to be alarming, up to 50% at times. Reading up on this issue over the internet I found people advocating Memory upgrade, if one ever experiences the ratio exceeding 10%. Though, what I find most peculiar is the fact that during my extensive use of the CPU or Memory, the amount of Free Ram almost never drops below 2Gb, the all-time low being 1,65Gb. My first question is: why doesn't the OS use up all of the available memory when in need? Since I'm seriously considering upgrading memory, I find myself on the fence about such action, because I don't know if it will serve the desired effect I'm looking for (reduce the ratio and improve multitasking)? Would replacing the current HDD with a faster one also improve performance?