There can be multiple reasons for this.  The most likely is that the IP address you are using for your VPN is on a local area watch list and all of your information is going through extra levels of scanning by the government.

China uses multiple levels of internet monitoring.  They have government level, province level, city level, Internet Provider level, keyword level and "known IP" level scanning.  And most of these levels do not talk to each other, so depending on the situation, your information can be going through multiple levels of scrutiny before it gets to you.

For VPN's, China will buy a membership and discover all of the IPs it uses, then put them on a watch/block list.  So if security is important, it is important to use a VPN provider that has lots of IPs for you to switch between.

For example, the VPN I use has over 10,000 IPs and I can schedule automated switching between IPs every 5 minutes if I wish.  And, it also does 256-bit encryption as an extra level of protection against being snooped on.

256 bit encryption sounds good, but is unnecessary since 128 bit will take several lifetimes to crack if it is an encryption with no known holes.

What is told about the monitoring sounds like rumors. The government cannot snoop into your traffic if you're using a safe provider.

Anyway, back to topic:

The speed is of course based on your slower connection in Tianjan

If your computer is acting up, I am sure it has nothing to do with hackers, but it sounds more like either Spyware or your computer is simply clogged up with too much software.

What I would recommend you to do is to keep task manager open and see if any programs are using a lot of CPU (20%<) or memory.

IM like QQ, Skype or MSN can cause this, but no matter which program it is then upgrade to the newest version.

I doubt anyone can give a definitive answer to your problem without using your computer.

Computer Scientist here... 

As far as your PC freezing up, it could be overheating or it could be a failing hard drive..  On more than one PC I've seen here, the people who built it didn't lock down the heatsink properly so a big enough bump during a move was enough to make it fall off completely..  With a loose heatsink, your CPU will overheat in no time at all.  I'd suggest getting an application such as CoreTemp (it's free) to monitor your CPU temps to make sure it doesn't go above 60C or so, or your CPU will slow down automatically to prevent itself from burning up.

As for a hard drive, a big enough bump could damage it whether it is on or off.. Open up My Computer, right click on the hard drive, go over to the tools tab, and then run a scandisk (with both checkboxes checked!) on all your hard drives.. If it is your C:\, it will require you to reboot to do it.  If you don't run scandisk and you've got some bad sectors that the OS doesn't know about, it's going to try to correct it on-the-fly and it's going to make your PC feel very very slow for a while as the OS tries to move files away from bad/damaged parts of the hard drive..  It's better to run the scandisk tool which will find and attempt to fix all the problems if your hard drive has a little damage inside from shocks / vibrations / bumps.

Also, as somebody else said.. Make sure you're not running out of RAM..   If you run out of RAM, your hard drive will start swapping like crazy and the PC will feel sluggish.. If you see the hard drive chugging away (noisy and/or constantly solid activity light) then you know it's either a hard drive that has some problem or you're running out of RAM.

As for VPN, you should use anything that uses the OpenVPN protocol. You should *NOT* use PPTP protocol as traffic on this protocol is not secure.  I have no idea what StrongVPN uses, I run OpenVPN to my dedicated Linux server in the USA and never had any problems.

And of course, I hope everybody is using a decent anti-virus as PC viruses are all over the place here in China.. My girlfriend uses 360 and it seems to do a good job at finding viruses, fixing driver problems and other things (360.cn).. Of course, I personally trust whatever anti-virus scores well on the latest AVComparatives summary charts(av-comparatives.org).. Usually it's Kaspersky, Avira, Avast, or F-Secure.. AVG has unfortunately been doing worse and worse every year for the past few years...

Wow great advice here, thanks! I'm running an Asus G53 which I bought back home before coming to China and I have 6GB of RAM. I had a windows gadget that monitors the RAM usage and I push to about 50% with Skyrim and itunes running at the same time, otherwise always 30s.

The overheating thing helps a lot, thanks for the info about it!

The sluggishness only happens when I turn the VPN on. 

I'll digest VPN stuff slowly and try out all the advice. 

After a whole week of bad china days, thanks for turning it around by offering such in-depth help!

I suggest you to change your vpn service provider. Read this article i hope it helps you

http://www.bestvpnservice.com/blog/best-china-vpn-list-of-top-10-china-v...

Yes this is the common problem when you use VPN connection in China. I will suggest you to change your VPN provider because that will give you good connectivity with dropping down the speed of an internet. Whenever I went to China, I always used PureVPN. They have their own customize software for Chinese people through which they can get good connectivity. 

Don't like that best vpn list...try Astrill, I've had no problems anywhere in China..and the price is fair : $5.83 a month (if you get for 1 year)...you won't be disappointed

Probably the cia watching you

you simply contact the company which provided you VPN service..they will explain you better...may be in Tianjin you are running on ADSL rather than Fibre..

Contact the your vpn customer severice.all the problems will be fixed.

I use Express VPN and although it is always very good, this morning it will not connect to anywhere. I think "they" are messing around again.

Because my previous VPN gave up a few weeks back, I signed up yesterday to ExpressVPN. I, too, cannot get a connection through any of their locations.

Some SSL certifications has been blocked.  Try securityvpn.org. It's work well now!

I find the best source for resolve this problem check this i hope it helps you CHINA VPN this is the world no1 vpn information website check this

Thanks

The countryside blocks all my VPNs. Don't want those farmers learnin' nothin', eh?