In the main the only thing that I have ever messed around with inside PCs and laptops is RAM. When computers become sluggish, (despite all manner of regular scans!), I just upgrade the RAM.
If your system is not maxing out the RAM use, adding more RAM won't make much of a difference. 8GB is more than enough for basic web browsing. You'd get a bigger performance gain by installing an SSD.
Thanks for all tips. Like the Old Timer scan. I am getting a laptop and will then start messing with the PC once the laptop is capable of the PC's tasks! Updating the BIOS and then swapping the RAM around. Your comments have been a real education! I have been watching the Windows Task Manager....Performance. Typically the memory usage runs at 88%. (There are 4 blocks of 4GB seen but only 2 of them active! So that is 88% of 8.183GB). I think that ultimately it will be a new motherboard and an SSD!