That's a nice computer, even by today's standards! I would opt for upgrading the RAM to 16GB if you are truly concerned, and REINSTALLING Windows, even upgrading to a newer version (if applicable) would also be a great idea. If you need the stuff on your computer, you can always use an external SSD or HDD. This will allow your computer to run WAY faster, when using the HDD.
Finally, I would also upgrade your graphics card, and down the road maybe your CPU.
This is a great computer, and I wouldn't replace the whole thing for a while.