You got a new computer, or you want to buy a new computer. This means that you are interested in testing your old computer and it's performance to know if you need to move one. You have to test the performance of the new computer.
What to do ? Well, depends on what you want to test. If you are interested in a single aspect you can open 20 programs and see how fast opens them all.
Well, that is just basic test and you can't take any conclusion. There are many softwares that can test your computer components and compare them with new ones.
The proccess is called benchmark and you can find a list with benchmark software here. VDDFEFJVA4E9