Nice article. Too bad it's not quite entirely correct.
Adding more RAM will NOT necessarily speed up your computer. It depends on whether the particular mix of applications you are running uses all of your existing physical RAM to the point where the system has to swap part of memory to disk. If you're running into that situation then adding more RAM will improve things, otherwise no.
Additional RAM will allow you to run more applications simultaneously but won't necessarily speed your system up.
My first system had 128K of RAM. I doubled that to 256K but the system didn't run any faster. It did make a difference as to which RAM hungry applications I could run or not.