tabs.warmup()

To optimize system resource usage, browsers may drop GPU resources associated with tabs that the user has not accessed for a certain amount of time. If a browser has done this for a tab, then reactivating the tab (for example, when the user switches to it) may take longer than it normally would.

The tabs.warmup() API enables an extension to start the process of rendering the resources for an inactive tab, if the extension expects that the user might switch to the tab soon. This then makes the actual tab switch faster than it would be otherwise.

Note this API does not work on discarded tabs and does not need to be called immediately prior to switching tabs. It is merely a performance improvement when the tab switch can be anticipated, such as when hovering over a button that when clicked would switch to the tab.

It is expected that this API would mostly be useful to tab management extensions.

This is an asynchronous function that returns a Promise.

let warming = browser.tabs.warmup(
  tabId               // integer
)

function onSuccess() {
  console.log("success!");
}

function onFailure(error) {
  // e.g. ID of a nonexistent tab
  console.error(error);
}

async function warmupMDN() {

  const mdnTabs = await browser.tabs.query({
    currentWindow: true,
    url: "https://developer.mozilla.org/*"
  });

  if (mdnTabs.length > 0) {
    const warming = browser.tabs.warmup(mdnTabs[0].id);
    warming.then(onSuccess, onFailure);
  }

}

browser.browserAction.onClicked.addListener(warmupMDN);