The CPU & Memory Panel displays the CPU, polyphony & memory usage for the project. There is a CPU Panel tutorial video here.
RAM vs Address space - The amount of 'RAM' you have installed in your PC and the amount of working 'Memory address space' programs running on it have access to are unrelated. Forget how much physical RAM your PC has. All 32-Bit programs can access a maximum of 4 GB 'working memory' and up to 192 Gb for 64 bit programs depending on your version of 64 Bit Windows (see 'Increasing FL Studio working memory allocation' below).
NOTE: Each program is given its own working memory address space that is simply an location of memory addresses where the program can save and retrieve data as it operates. If there are 4 programs running, there may be 16 GB of working address space allocated between them. The programs don't know or care how much RAM your PC has, managing memory allocations is up to the Windows Operating System.
If there is not enough physical RAM to accommodate all the working memory allocations, the Windows Operating System shares the RAM among the active programs and makes up for any shortfall with a special file on the hard drive acting as an extension to the RAM. In this way, the working memory addresses for a given program (FL Studio for example) may point to your physical RAM (winner!), the hard-drive Page File (loser) or a combination of the two (win some lose some). It should be clear that the more physical RAM you have, the more likely it is that a program will win the RAM allocation 'lottery' and have all its working data stored there. As physical RAM is much faster than the hard-drive, programs run faster. For FL Studio, having lots of physical RAM means you are less likely to experience buffer underruns as data is streamed (slowly) off the hard-disk. What RAM does not fix is 'out of memory errors'.
Having 16 GB of RAM installed on your computer does nothing to break the 4 GB limit associated with 32 Bit applications, and that is what the RAM meter shows (depending on settings it will max at between 2000 to 4000). Even if you have only 1 GB of RAM you can still use the extension options below to increase FL Studio's access to working memory. This can be useful when working with very large audio files that won't load with the standard memory allocation. The simplest approach is to remove samples & instruments from FL Studio's memory allocation or if you need to give FL Studio itself more working data (where processes can't be externalized) increase FL Studio working memory allocation (see the section below).
NOTE: If you open the Windows Task Manager and examine the number of cores used and their relative loading, this is under the control of Windows. This may come as a surprise since marketing departments make a lot of noise about their multi-threading 'optimizations'. Really, all programs do is publish at least as many threads (independent processes), as there are cores available. FL Studio does that, but, it's the Windows Scheduler that is largely responsible for the core assignment. To complicate matters even single-threaded application may use several cores if Windows decides to flip core assignments at some point, and it often does. So what matters? - If you are testing and comparing CPU loads it is the number of plugins and/or effects that can be processed without buffer underruns and the FL Studio internal CPU meter. This is the real-world measure you should use. Don't obsess about how cores are used, particularly at low CPU levels, since the Scheduler will even out this distribution as CPU load approaches 100%. Registered users can see some graphs testing FL Studio core usage here.
These options allow you to use all the RAM installed in your computer to the limit of your Windows version. There are two options:
'Keep on disk' and 'Bridged mode' will significantly lower the memory required by FL Studio. Together they will allow you to run projects to the limits of your PC's capability and operating system (32 or 64 Bit).
Increasing FL Studio working memory allocation - There is an 'FL.exe' file in the FL Studio installation directory. Using this to start FL Studio after making the following changes to your Windows operating system will give FL Studio access to 3 GB or 4 GB (up from 2 GB) depending on your OS:
NOTE: From FL Studio 11 the 'FL (extended memory).exe' has been renamed 'FL.exe' and is the default executable after installation.