I have a Titan X (Pascal) from like 2015 with 12GB of vram and I've had no trouble running it locally. I'd say it takes me about 30 seconds maybe to generate a single image on a 30ddim (which is like the bare minimum I consider for quick iterations), when I want to get more quality images after I focus on a proper prompt, I set it to like 100 or 200 ddim and that maybe takes 1 minute for one picture (I didn't accurately measure). I usually just let it run for a few minutes in bulk of 10 or 20 pictures while I go do something else then come back half 15-20 minutes later.

It runs pretty well but the most I can get is a 768x512 image, but it's pretty good for stuff like visual novel background art[0] and similar things.

[0] - https://twitter.com/xMorgawr/status/1564271156462440448