function createPreloadedNewTab (win) {
  var id = win.id
  if (_createPreloadedNewTabTOs[id]) {
    clearTimeout(_createPreloadedNewTabTOs[id])
  }
  _createPreloadedNewTabTOs[id] = setTimeout(() => {
    _createPreloadedNewTabTOs[id] = null
    preloadedNewTabs[id] = new Tab(win, {isHidden: true})
    preloadedNewTabs[id].loadURL(defaultUrl)
  }, 1e3)
}
NOTE
preloading a tab generates a slight performance cost which was interrupting the UI
(it manifested as a noticeable delay in the location bar)
by delaying before creating the preloaded tab, we avoid overloading any threads
and disguise the performance overhead
-prf