Your computer's performance has a lot do with RAM. The software applications installed on your computer depend on Random Access Memory (RAM) to keep them running while you're working. RAM functions as the computer's short-term or temporary memory. It stores the data you input into an application. RAM is only responsible for holding data while an application is running. Once the application is closed, the data is lost.
Relationship with the CPU
RAM works in conjunction with the central processing unit (CPU). If RAM is the temporary memory, you can think of the CPU as the brain of the computer. The CPU chip retrieves data from the RAM. The chip takes those instructions and begins to move and process data through the motherboard in the correct order to its next designated location. The CPU runs the computer the same way the human brain performs certain tasks that affect your senses, emotions and abilities to physically move and speak. Without the CPU, your computer will not be able to perform any of the functions it's designed for to keep your computer running efficiently.
Aiding the CPU is the RAM's ability to process data quickly. Each application requires a minimum amount of temporary memory to operate efficiently. Applications that require graphics need more RAM than applications without graphics. Whatever task you perform within an application, the RAM provides the required amount of memory to run each application while also storing the data of the work you're performing. Keep in mind that having more than one application open reduces the amount of temporary memory available to move data between the open applications and the CPU.
You have two options to keep communication lines clear between the RAM and CPU. You can have a lot of RAM available or keep no more than two applications running at the same time. Running multiple applications is similar to buildup in a drain. Just as buildup slows water flow, running multiple applications clogs up the temporary memory preventing RAM from passing along and processing data to the CPU. If the CPU is not retrieving data to pass through the system, everything stalls. Usually the computer displays a box warning that the virtual memory is running low. At this point, it's probably best to save your work and close a few applications. Once you've closed a few applications, the RAM and CPU return to the tasks that allow your computer to perform at top speed again.