Before swapping the hardware out, it might be a good idea to make sure you are using the latest driver software for your existing card. As the computer is six years old, I assume that Windows or whatever operating system you are using has been updated over time. I suspect that generic drivers have been installed by Windows that allow the card to work, but not perform particularly well.
Go to the AMD website and download and install the latest available driver software for your video card. I would expect that the performance can be dramatically improved over what you are currently seeing.
Unless you are a gamer or using ultra high graphics settings, a gigabyte of video RAM should be more than enough to display HD quality images on the screen.
Generally speaking, basic default video graphic facilities are included on the computer motherboard. A video card is installed to improve the graphics. There is also the possibility that your computer is currently defaulting to use the motherboard display driver and not using your graphics card at all because the driver software for the graphics card is not up to date, or is incompatible with the latest operating system software you have installed. A performance measurement showing only 2% of the potential maximum suggests that the motherboard might be providing the video output, rather than the video card.
The video graphics card itself may be faulty, or the connectors have developed a bit of high resistance. Unplugging and reseating the graphics card is the first thing to try if a software update doesn't work.
Don't spend money until everything else has been eliminated.
A new graphics card will completely replace your existing one.