Computer seems slower by time. People thought the computer was faster when it was new. It becomes slower by time. So he need to upgrade it. Conventional up gradation is to increase RAM (Random Access Memory), some people upgrade by changing processor also. Most of the people through out his computer and purchase new one.
I am suggesting to upgrade with some strategy.
Purchase SSD:
SSD (Solid State Drive) is not disk but NAND chips. Using SSD instead of Hard disk will increase your computer performance magically.
When you start your computer the starting operating system takes time. The hard disk round and head read data from disk and converts digital signal and placed on RAM. But SSD is electrical cheap that need no round of disk. It just acquire data from NAND chips.
On avarage the data transfer rate of SSD is 10 times faster than HDD. So just replacing hard disk can be good upgradation strategy.
Graphics Card and RAM
Most of the computer use the motherboard built graphics card. The build in graphics card hold the a part of RAM of your computer. If you don’t have Graphics card you can purchase one and upgrade the RAM.
Processor Upgrade:
Processor upgrade is minor upgrade to me as upgrading processor means purchasing a new computer. However upgrading processor sometimes needs changing mainboard and RAM as well as.