ATi Radeon issues

I just switched my son's computer to one that has a Radeon 5450. A low-end card, but still it should be better than his old computer's Intel GMA 2500. It's running the radeon open source driver and performance in minecraft (the only app that's relevant) is worse than before. I couldn't just take the video card and put it in his old computer--it's a small form-factor with no slots. This is Fedora 25, like it was before. The new computer has the same processor as the old, though less RAM (5GB v. 8GB--unfortunately I was not able to swap it over). I see lots of conflicting info online about whether the fglrx driver works on newer kernels, and I don't want to do anything time-consuming to get it to work. Is it easier than I think? Should I just buy a cheap NVIDIA card, or will that be a hassle too? Or is the RAM the issue? All advice welcome. Thanks! Matt