Bottleneck
Bottleneck
Generally, when you're completely CPU-bound reducing graphical settings won't boost FPS further. The "world" inside the game, all events, NPC actions, and your decisions are handled by the CPU. The GPU only renders the images you see, which the CPU instructs the GPU to create. If the CPU is already at full capacity and can't process tasks quickly enough, the GPU's work on drawing won't improve performance since it's already doing very little.
I have a GTX 1050 Ti connected with an i5 3450. I’m thinking about switching to an RX 580, but I worry it might cause a bottleneck on CPU-heavy games, possibly lowering my FPS more than now. Also, I don’t have the budget for a processor upgrade, so should I go with the 580 or keep things as they are?
It would never be better. Just opt for a 580 or 570, as your GPU is limiting your CPU performance a lot.
It is indeed possible, you can transition from low but stable frames to high but choppy frames
If you were in my position, would you do it? Do you have any experience with unstable FPS and how was your experience?