I think China likes to operate it's own ad networks, and certain ad networks from outside the PRC are blocked or slowed down. e.g. Google's AdSense and DoubleClick. Probably the same with some tracking and usage networks. I did try using a proxy as well to view SF, but it didn't seem to make much difference.
However all is not bad, I found a good way to browse and post on SF with phones and tablets, Opera Mini. http://www.opera.com/mobile/ Works on Android, Blackberry, iOS, Symbian, Windows Mobile and Java. Opera's servers compress and process complex webpages rendering them suitable for viewing on a mobile device using the Opera Mini client. Seems to work just fine with SF2.0, loads quick as well. Great for anyone with a limited 3G data allowance, because Opera Mini is only downloading a highly compressed version of the site.
About the CPU hogging and the long loading times, I think I solved this as well. I have Ghostery for Chrome, this shows what third-party ad and tracking networks a site uses. So I could possibly see what was causing the hangups. It showed Facebook, Google Adsense, Google Analytics and Quantcast. I know Facebook is unreachable here, if one tries to access Facebook.com directly, the browser will just sit there repeatedly sending requests to a server which is not there. Some of Google's non-Chinese services are blocked or can be very slow.
So I've added the domains for these sites into my hosts file, along with a few others like DoubleClick, Comscore and Omniture. This means that any browser on my computer will get an immediate 'Not found.', instead of fruitlessly trying to access a third-party site it can't get to. Doing this seems to have improved quite a few sites for me, although these where not as bad as SF.
There is another thing which I've observed with some websites, not because they're blocked, is that they'll ignore HTTP requests from Chinese IP addresses. Presumably because of security concerns, botnet DDoS attacks, hacking, much of which seems to originate from China. So what happens the browser appears to be loading a page, but will just sit there repeatedly sending HTTP requests and eventually gives up after a couple of minutes.
Done the same on my UMPC/Netbook hosts file and SF appears to be usable on there, although it's not perfect, there is still much horizontal scrolling here.
Of course I'm no longer being tracked by any of these peeps anywhere,