github-instant.js

// ==UserScript==
// @name         GitHub Instant
// @description  Preloads GitHub content on link hover. CC0 Public Domain.
// @version      1.0
// @author       Alex Mattrick
// @match        https://github.com/*
// @match        https://gist.github.com/*
// @icon         https://assets-cdn.github.com/favicon.ico
// @require      https://cdnjs.cloudflare.com/ajax/libs/instantclick/3.0.1/instantclick.min.js
// @grant        none
// @grant        GM_addStyle
// ==/UserScript==

function cleanup(body) {
  var jQ = $(body);
  jQ.find('.header, script, .btn-danger, .dangerzone, .file-navigation-option').attr('data-no-instant', '');
  jQ.find('a.header-logo-invertocat, ul.header-nav.left, .header a.dropdown-item').attr('data-instant', '');
}

cleanup(document.body);
GM_addStyle('#instantclick { display: none; }');

InstantClick.init();
InstantClick.on('receive', function (url, body, title) {
  cleanup(body);
  return { body: body };
});