Chinese websites loading slower recently?

All, I know that access to Chinese websites from outside China is notorious for being slow or broken, but we seem to have had a major increase in support calls from our users over the last couple of weeks, complaining of slow or no access to major Chinese websites, such as www.baidu.com, www.youku.com and world.taobao.com. We can't find anything on our network that would be affecting this, and at various times can (and cannot!) reproduce it with off-net connections, which would indicate that it's an intermittent, but widespread issue. Is anyone else seeing an increase in problems related to Chinese websites? Thanks in advance, Simon