With a 1080 GTX, at 3440x1440, with an i7 7700K, and most things turned up to max, I'm generally hitting my max FPS limit of 98 in "open" exploration. With my monster build (stone pyramid, with a 34x34 (of 2x2 stone floor blocks) footprint (34 blocks high) - 13-14,000 instances), and fairly heavily modified terrain, it will drop to more like 45-50 FPS (depending on what graphics features I turn off, and how many flames are actually flaming).

Writing graphics software for Windows is never fun or easy - the ability for the consumer to have pretty much any combination of hardware, drivers, and settings, is a nightmare for the developer. (And, yes, I speak from painful experience.)