bugs in the menu, the game, spawning mobs

Error in the menu. When creating the world, it can sometimes lag and crash. When enabling resource packs, Minecraft may also crash. In the worlds, it very often happens that mobs do not appear for a long time, from one to three game days. The menu in the new snapshot is pretty bad, few people will like it. Immediately after creating the world, even at a short drawing range, lags very much, lags from one to six minutes. That's all I've found so far.