Every time you open a program, it gets loaded from the hard drive into the RAM. This is because reading data from the RAM is much faster than reading data from the hard drive. Running programs from the RAM of the computer allows them to function without any lag time. The more RAM your computer has, the more data can be loaded from the hard drive into the RAM, which can effectively speed up your computer. In fact, adding RAM can be more beneficial to your computer's performance than upgrading the CPU.
To check how much RAM a Windows computer has, open the "System" Control Panel. This can be done by right-clicking "My Computer" and selecting "Properties..." To view how much RAM is installed in a Macintosh computer, select "About This Mac" from the Apple Menu.