The only thing in common, is the web site. 
Come off it, it's the device, it's the isp, it's the packets. It's.... Ffs it can't be all of those. 
That's why I posted up what I think the reasons can be for half of the home page to be displayed. To try to clarify what is and isn't likely causes

. And why I don't think its the web server or the primary database server (after looking at the code).
Current webserver load is:
19:51:04 up 2 days, 5 min, 1 user, load average: 0.00, 0.01, 0.05
I'm not bothered personally, it's only a refresh page away from being quite normal. Bar the lag of course, which seems fine now.
Cause of yesterday's cock up was discovered, and caused the primary database server to be slow to retrieve non cached data. Was you getting half loaded pages yesterday during that problem (approx. 17:15 - 20:15)? I wouldn't expect it after looking at code, but you may have got partially loaded pages at the end of the header section (so just above Newbies) or just after Parts for Sale. I'd be surprised if you got it halfway through the boards (or if you did, unrelated to server issues).
The simple machines web site is dog slow. So nothing to worry about really. (Loads the home page fine though
) ipad on wifi via Virgin media. Btw.
Interesting you find SMF's site slow, as its usually reasonably quick for me. There may be a pointer there

Do you ever use your Windows PC for OOF (or SMF for that matter)? If so, do you see similar?