Lower request and response time repos

I am playing around with GitHub API and I am wondering whether there is a way to limit the response size, because I want to return only a few fields instead of calling for the whole JSON. 

My main aim is to limit the time of the response. Using plain GH api it works ~185ms, and I want to achieve at least 50ms. Is that even doable at all?

I know that certain APIs have the possibility of limiting by the query, like adding ?fields=field1, field2, etc, that I want specifically to return, but I am not able to do this for GitHub API, or I don’t know how to do this.

For instance I would like to get only id, name, and private from https://api.github.com/repos/octokit/octokit.rb.

I am using Jackson and consume via RestTemplate. Is that possible with REST to lower the response time?