When FPS drops below 60, since ore physics are tied to it, they start moving in slow motion. I suggest playing on desktop where performance is a lot better.
Additionally yeah, in the late game due to various factors such as high force scaling, the ores can spend more time in the air than on the ground, which I don't like since I prefer seeing big beautiful gem piles. This will be improved by diminishingly scaling and capping force, as well as slightly increasing gravity, and hopefully making mountain reclaiming less aggressive as I continue to improve performance. But I'm open to other ideas how to make this better.
As for the souls, well, it's suppose to be a rare resource that you might not necessarily get to always use on every single upgrade, however I will be certainly adding more ways to obtain mithril and souls, through artifacts, prestige, boss kills and rituals.
Thanks for feedback!