To what do you refer?

Aside from the websites that are blocked in China, service providers have their own list of blocked sites (Unicom is particularly bad), and depending on the provider, various sites will get hijacked by advertising. All these problems can be overcome by a VPN.

Internet speeds in China are generally poor, and service providers will often sell you a package which works fine for a few days/months, after which time the speed becomes incredibly slow. Whether they are letting others use your bandwidth or something else, I don't know.

Is your problem one of the above?

Yes, it appears that speed has slowed down a lot for those sites I visit regularly, sometimes even not connecting. I wonder if my current location has anything to do with it. 

Our colleagues in Shanghai are experiencing difficulties in these past days. Our offices are connected to the servers in Italy for mailbox and VOIP. It's been confirmed by our IT provider in HK that lately the speed of data from China Mainland to the rest of the world has greatly deteriorated.

In Suzhou, it sucks if you try to access anything outside of mainland, but it sucked consistently for 3 years. I was in Hefei last week-end, it sucked less.

Official blacklist has drastically grown in the last couple of months.

Other than that, access to local servers feel like an intranet, while access to the rest of the world is slow/unstable.

I'm getting a feeling that whatever amount of bandwidth is shared in a building/area/district is primely distributed to local access, while "foreign" access gets the leftovers if any. I'm not sure if technology would allow that, but this is the best explanation I have for how it feels globally.

Internet very slow on any foreign website in these past 2 days and most of the ones I visit not reachable.

I'm listening to the footy right now and it's the clearest and fastest it's ever been!