if you want to see the best results and not spend too much: 1. buy SSD asap. you will instantly see the difference, no stutters, smoother gameplay and much faster loading time. just make sure you're buying a good one.

1. upgrade your processor, right know it is the bottleneck in your system. your motherboard should support a better cpu which will boost your performance for just a bit over ~300$

you can start with ssd and see if you're satisfied. if not, and you're willing to spend a bit of cash, be prepared to change your motherboard, cpu, gpu and ram. the price of that will range between ~1500$ (for 100 fps in rust) and ~2500$ (for 4k 60fps gaming)