I've seen this before from time to time. First question is what browser are you seeing this in? Second question is does a page refresh correct the layout (it almost always does for me, when I see it)? Is there anything consistent that you're doing when you see the page display this way?
Just an observation here, but it appears that you're seeing this while trying to log in...what happens if you stay logged in by checking the Remember Me button?
As for the "slowness" thing....I'm not seeing that at present, though I do sometimes. That could be a simple traffic issue/bottleneck somewhere along the way.