I'm thinking a very slow CPU, off brand PSU which is, at best, a 600w unit, and the fact you only have a single RAM stick, that upgrading the GPU is a BAD IDEA, and won't do anything to solve your problem. You need to upgrade your entire system.
Despite other comments, yes a GPU will help your overall performance in your system. I've seen people using a KOLINK power supply running a 1060 with an i7 7700k. If your PSU has the necessary PCIE connections to power that card then go for it. Your CPU may bottleneck it, but that's fine until you get enough money for a platform change to something like Ryzen.
I recommend looking at the Ryzen 5 1600, specifically the 12nm refresh of that chip. It's a great bang for the buck CPU at $85 for what is essentially a 2600.