Created attachment 232182 [details] MiniBrowser screenshot loading the file in a local URL If you download the file in the URL (http://people.igalia.com/mrego/css/perf/grid-200.html) and you load it locally, you'll see that MiniBrowser needs a lot of time to finish loading it. At least if you open the inspector and check the newtwork requests information, loading the file (5.17 MB) is taking 30.04 seconds in my machine.