That AMD card is from 2013, so yes, it's time to think about replacing it. Although it does support DirectX 12, it's so old that it will probably be left behind any day now.
Whether that's the actual cause of slowness is difficult to say. The trouble with GPUs is that they sometimes give unpredictable problems. An RTX 2060 should certainly work well.
On my own system (i7-9700K, Quadro P2200) a surface blur on an "average" 8K file completes in about 35 seconds at 70 pixel radius. I've no idea how normal that is, but this machine has worked well and not given me any cause to complain.