Slooooow Internet for direct downloads ONLY?!

For the past several days / last week or so I have been unable to direct download things like podcasts. 

They start off slow and dwindle away to nothing before finally just crapping out.  This happens across multiple websites, but what I mostly download is podcasts from BBC, Chinesepod, podcast aggregating sites etc.

Here's the weird thing - the rest of the internet works fine (by China standards), web pages load up quickly, and torrents work fine.  Even weirder, when I use my free but unreliable VPN, direct downloads not only work, but I can sometimes get speeds of up to 300-400 KB/s when normally i can only get 200kb/s at the most.

It's like my connection is being choked.  Do such things as monthly caps exist in China?  I am in Shanghai on China Telecom, 2M connection.

I think it is just lack of bandwidth. The exact same thing happens to me but only at peak times when too many people are online. For me it stops when it is not peak time. I guess the VPN bypasses the choke point.