[tedd4u]

One packet is great if you can do it. There's a big penalty after the sender in a new TCP connection reaches the initial transmit window. A lot of sites these days have configured this up from 2x or 3x MSS to 10x MSS (about 5,360 bytes) to increase what can be sent in the first transmission back from the server (HTTP response for example).

[Dylan16807]

If they're configured for 10x they're probably also going to be using an MSS of 1460, so you can cram 14 kilobytes of data into the initial request.