Shaders and shadows are optional. They will create little to no lag as long as you have a computer that isn't from the friggen Jurassic Era. If your computer cannot handle the new effects, you can simply turn them off. Terrains and interiors are not going to be kept in the game and toggable, because they cause problems with the engine and they simply need to go so Blockland can get more updates and improvements.
Every time someone is blindly defending terrains and interiors, and saying we need to keep them no matter what, you basically don't want Blockland to get anymore updates and improve. Terrains and interiors are the reason we barely get engine updates like the Brick Physics update, and every other update is just adding a default add-on.