No free service is truly 'free', they are restricted in some way or you have to give something up.
They typically have one or all the following issues:
Ad Supported.
Speed (slow)
Heavily restrictive data limit (ie. 500mb)
They run of Peer to Peer which means other people are using your internet to brows anonymously. (Bad, ie. Hola)
Latency (slow)
If your serious about using a VPN just buy one that fits your needs, you can get full featured services from £40 a year. Tor Guard, PIA, Tunnel Bear to name a few. Just read the small print carefully as to what is and inst allowed on their network.
I've just renewed with ExpressVPN. Excellent speeds and totally unlimited. Doesn't come cheap though - about £80 for the year.
They suggest different servers for different uses, have a look into which server you're suing and try a different one. Also it depends on what the device running it is, for example OpenVPN isn't multi-threaded from memory, I forget it's limit speed wise, but it was lower than 200mbit, also don't forget the 'up to' proviso from VM may mean you don't get 200mbit.
VPN sites are blocked at work so I cant check but do they support any other protocol like that you can try as someone above says openvpn isnt the fastest.
Are you the client or have it set up on a router? It apparently takes quite a bit of grunt and home routers are often not up to the job.
