Spelunking on a brand new world with a stone sword, some torches, a stack of logs and a few bits of raw chicken wasn't much fun when I had zombies coming from just about everywhere, though. Cows aren't nearly common enough, or drop leather enough to make leather armour that early in the game, and even if they did you'd be saving it for the enchanting room anyway. Iron, of course, is why I would be spelunking in the first place; the egg has to come before the chicken. I can see how the Zombie change is useful for exploring paths you might have missed, though, and generally makes the game a lot more challenging... they just need to correct the Zombies-not-actually-breaking-doors glitch.
Not actually encountered a spider with attributes yet, so can't comment on that.
The low FPS problem seem to be caused by the new launcher apparently not wanting to choose integrated graphics cards (mine's HD 4000, which I know is a very ordinary GPU) when loading the game, so if you've got a separate graphics card you shouldn't have a problem. I don't know why Advanced OpenGL works, or even what it is, or why that affects servers, but I've gone from 8 FPS to 50 FPS now. Computer science ain't my thing and that really showed when I worked on the Crew, so... I ain't got a clue.

It's strange that this is the 'Horse Update' and not one of us has even mentioned it yet.