From what I've experienced the game renders tessellation bricks nearly as fast as vanilla bricks, with the only real caveat being the increased Vram usage. Blockland doesn't use much Vram to begin with and with Top Mode set to Textured and everything else turned on I've been able to have 256,000 tessellated brick loaded at once. I have 2 GTX 1080 Ti's so your results might vary.