If a TCP connection is established between a client and server, is sending data faster on this connection-oriented route compared to a connectionless given there is less header info in the packets? So a TCP connection is opened and bytes sent down the open connection as and when required. Or would UDP still be a better choice via a connectionless route where each packet contains the destination address?
Is sending packets via an established TCP connection (after all hand shaking has been done) a method to be faster than UDP?
I suggest you read a little bit more about this topic.
just as a quick answer. TCP makes sure that all the packages are delivered. So if one is dropped for whatever reason. The sender will continue sending it until the receiver gets it. However, UDP sends a packet and just forgets it, so you might loose some of the packets. As a result of this, UDP sends less number of packets over network.
This is why they use UDP for videos because first loosing small amount of data is not a big deal plus even if the sender sends it again it is too late for receiver to use it, so UDP is better. In contrast, you don't want your online banking be over UDP!
Edit: Remember, the speed of sending packets for both UDP and TCP is almost same, and depends on the network! However, after handshake is done in TCP, still receiver needs to send the acks, and sender has to wait for ack before sending new batch of data, so still would be a little slower.