I test Zentura on a cheap laptop with an Intel N100 on purpose. If it runs well there, it runs well for almost anyone.
This was a few days of performance work. Forests were the worst part, so leaves are now flat cards with outlines on Low, trees share their geometry, and the block and bark shaders got simpler. Characters are one mesh each instead of many pieces. Chunks of the world are merged so the graphics card gets fewer, bigger jobs.
The result: the whole island, trees and grass included, at over 200 fps on Low on that laptop.
The higher settings got some love too: proper shadows, no shimmering on far-away blocks, and the world streams in about four times faster on Max.